On Apothecia Occurring in Some Scytonematous and Sirosiphonaceous Algæ, in Addition to Those Previously Known

On Apothecia Occurring in Some Scytonematous and Sirosiphonaceous Alg, in Addition toThose Previously KnownAuthor(s): William ArcherSource: Proceedings of the Royal Irish Academy. Science, Vol. 2 (1875 - 1877), pp. 85-93Published by: Royal Irish AcademyStable URL: http://www.jstor.org/stable/20489992 .Accessed: 16/06/2014 13:30

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ARCHER-On Apothecia in A ate. 85

XV.-ONx APOTHRCIA OCCURRING IN SOME SCYTONEMATOUS AND SiuoSr r'HONACEOrS ALGE, IN ADDITION TO TIOSE PREVIOUSLY KNOWN. By

MILLIAM ARCHER, M. R. I. A. (With Plate 6.)

[Read December 14, 1874.]

It is now some years since, upon examining some examples of the by no means uncommon plant, long (and by some still) accepted as algal? Stigonema atrovirens, Ag., that I was attracted by the peculiar en largements of the branches, and was much interested in perceiving that this plant showed, imbedded in these swellings, distinctly lichenous fructification-apothecia, as well as the so-called spermogonia. Upon searching out the literature of the subject, I found from Bomet's valu able paper* that my discovery had been previously well known, and that my specimens fully bore out the description he gave, with the exception of the hyphe subsequently discovered by Schwendener. Bornet, indeed, argued from the fructification which he had proved to belong to this form, that it shouldl no longer be accounted an alga, but relegated to the lichens as Ephebe pubeseen8.

But it occurred to me that Bomet's supposition, at the period of his writing the memoir on Ephebe, that other forms of apparent affi nity (Stigonenma mamzillo8um, St. mammniferum and others) were of another and different nature-that is, "alge," whilst E. pubescens was a " lichen,"-could not be borne out.t It struck me, indeed, that if Stigonema atrot'irens were no alga, buit a veritable lichen, that then the other Sirosiphonaree and Scytonemaece., if likewise patiently ex amined, must prove themselves of the samne nature. Stigonema mamil Iosum and Sirosiphon- and Seytonema-forms, I thought, could hardly be less lichens than .Ephebe pubescens itself; nor was I then aware that such in some cases had, since Bornet's paper referred to, been actually accepted as a fact.

Having at that time more frequent opportunity of finding, amongst the Wicklow hills, the commoner representatives of the class than more recently, I then made a considerable number of gatherings and ex amined them as closely as I could for " apothecia." I found it a more tedious labour than might be supposed, for, though I by and by found apothecia in three genera, I had to make very many hundred gather ings and examinations in order to be successful in encountering even a few "fertile" specimens; for, though possibly more frequently " fruiting" than one might suppose from that fact, the opacity and

* Bornet, "Recherches sur la Structure de VEphebe pubescen*" in

" Ann. des

Sei. Naturelles," 3 ser., torn, xviii., p. 155. t Bornet, loc. cit., p. 167. R. I. A. PROC-, SER. II. VOL. II., SCIBNCe. N


http://www.jstor.org/page/info/about/policies/terms.jsp

86 Proceedings of the Royal Ir ish Academy.

closely tufted habit of most of these forms contribute to rendering the little dark lateral tubercles usually formed by the apothecia somewhat readily overlooked, whilst they might in some forms be even passed over under a low power (the only useful way of searching) as merely rudimentary " branches."

It is matter of regret to me now that I did not at the time bring forward some notes upon these forms before the preparations I had

made had become spoiled; and it is also a matter of still greater regret that I did not secure some drawings more in detail than the rough sketches I am able to offer. But as even a chalk drawing on a black board is better than none, so the accompanying figures (Pl. 6) may serve a temporary purpose until better are forthcoming from some source,

whilst the figures of the spores themselves may be accepted as accurate. I at once assumed from our knowledge of Ephebe pubescens, coupled

with the additional fact of having found apothecia in Scytonema, Sirosi phon, Stigonerna (mamillosum), that these genera and probably the whole of the Scytonemaceew and Sirossphonacew, could be no longer properly accounted algae, but should be relegated with Ephebe to the lichens.

But another and a different solution is put forward now-a-days by Professors de Bary and Schwendener, and those (Reess, Bornet, Treub, and others) who accept the new doctrine of the nature of lichens. It has, as is well known, been previously long supposed that, assuming the gonidia to be really organs of the lichens, these may here and there (and by no means unfrequentlv) become detached from the parent plant, and, under conditions unfavourable to their forming a new lichen, carry on an independent (probably abnormal) alga-like existence; and hence that many of the so-called unicellular and some of the filamen tous algal growths, which may have been regarded as specifically dis tinct organisms, should really be expunged the list of independent plants. On the other hand, Schwendener and the new school hold that the " lichen-gonidia " are veritable unicellular, or, as the case may be, according to the type of lichen, filamentous algse which vegetate within the lichen-thallus as the serviceable (assimilating) host plants of a parasitic ascomycetous fungus, the " lichen-hypha." A resume of the whole question, of the views put forward and the arguments adduced, so far as the discussion has reached, both for and against, I have recently endeavoured to bring together, and it is hence super fluous to attempt here to recapitulate the particulars and points of his hypothesis, except as they bear upon the group immediately in question.

In his able and interesting work on the " Gonidia-forming Algal types,"t and beginning with the '& Phycochromaceous " series (Nosto chine, Niig.), Schwendener places the Sirosjphonacea in the front rank.

* "Quart. Journal Mic. Science,'* vol. xi?., N. S., p. 217; also vol. xiv., p. 115

in which places the references to the various authors are given. '

t Seh wendener: "

Die Algentypen der Flechtengonidien," Basel, 1869.



XARCHER-Un Apothecvia int Algr. 87

Ile justly observes they should begin the series, amongst the bluish green filamentous forms, by reason of the well-expressed contradistinc tion offered by them between apex and base, also by reason of their being marked by a formation of true branches, as well as, in their higher representatives, showing an evident accession to their thickness by subsequent growth. Possessing these specialities, they at the same time, however, show an unmistakable affinity on the one hand to the

&cytonemea and Rivulariew in the common possession of " heterocysts " and an apical growth, and on the other to the Nostochaceae, which,

wanting apical growth, form a transition to the Ocillariece. Prior to the propounding of the ne-w hypothesis, however, certain

of these forms, which, if met with without apothecia, would have been referred to the genus S&ytonema, had been found with apothecia and thereupon new genera were formed for them by Itzigsohn and Nylander tnder the names Ehebella, Itzigsohn, and Gonionema, Nyl. (or Ther

mutis, Fr. ?). In fact, they seem to have regarded the " barren " and the " fertile " plant as each belonging to distinct genera, even as ap pertaining to different classes-that is, that the "Ibarren" was to be accounted an " alga " and the "I fertile " a " lichen."

Of course, had Schwendener's view, but comparatively lately put forward, been then current, and had it been adopted by the discoverers of those apothecia-bearing Sirosiphonaceae and Scytonemaeee, the case would have been different: the new namne would in that case have been, as I take it, understood to be applied to the " new ascomyce tous parasite," within the Sirosiphon. or the S&ytonema-the double names should still pass current, for, in that case, they would stand for essentially distinct things, and no less so because these occur 8o0netimes living in consort and in a state of mutual physiological dependence.

The present communication, therefore, loses much of the signifi cance it might have been at least temporarily held to possess, from not being brought out at the time the observations were made, but aftet the new theory had been not only propounded, but had gained a large amount of currency.

Nevertheless, although more superficially put forward than if I had made the matter public at the time of the observations, and when these were fresh in my mind, this will, I think, be the first record of " apo' thecia " being noticed in at least five fresh forms or species referrible to separate

'I genera' (Scytonema, Sirosiphon, Stigonema) in the algal point of view. If this record had been brought out at that time, indeed, it would have pointed, as I should have taken it, to the assumption that these, in place of genera of alge, were in truth genera of lichens-not "f ew") lichens, but lichens not taken previously " in fruit."

With respect to Ephebe and Spilonema, Schwendener argues, that a genetic connexion between the hyphae and the gonidia is impossible. For the whole chain of gonidia leads onwards to the apical cell, by the unlimited subdivision of which new cells continuously originate, which are themselves again to be regarded as mother-cells (in those genera) of so many groups of gonidia. The assumption of a new formation of gonitlia by growing-lff from the hpha has no justification whatever;



88 Proceedings of the Royal Iiskh Academny.

those who hold such a view must take refuge in the assumption of the formation of the first gonidium in the germination of the spore-a -process which has not yet been observed in any lichen, and, d priori,

never will be. But it must be pointed out that, according to Schwendener and

others, Scytonematous and Sirosiphonaceous algie are claimed as form ing "gonidia " under two distinct circumstances or conditions: they are, according to their researches, to be found in certain lichens, either as mere accidentally detached portions of filaments wholly sunounded and involved by the hyphae, and caught up bodily in the substance of the lichen-thallus in a completely disorderly manner, or they exist as perfect plants of their type as algae, the alga-thallus quite unaltered in outward configuration, but permeated along the length of the filaments by the hyphae, which run between the rows of green cells. When the algte, as is assumed, are in the former way compelled to become the " gonidia-formers," it is the hyphe (not the algte) which must be held to control the configuration of the thallus and determine the character istic build-up of the " lichen; " when the algm serve in the latter way as gonidia to the intruding hyphm, the former (not the hyphae) retain their proper " specific " exterior, the build-up of the (algal) thallus is not externally altered, and it is onlly a microscopical examination which would reveal anything unusual or offer any "I chenous" indication. It is as regards this latter gonidial condition that Schwendener's argu rments, as to the impossibility of the genetic relationship of the hyphte alndl the young apical gonidia, by reason of the latter being formed prior to the arrival at the apex of the hyphal filaments, are directed, an(I to this condition it is that the notes here brought forward apply.

One of the most common of the S&ytonemaeee is the S&ytonerna myo chrous, forming silky cushion-like tufts on wet rocks, when dry, of

mouse colour, when wet, more of an olive hue; it seems to love best a pretty constant trickle, and if the force of the little current be some what strong, the mass may form a rather long drawn-out pad, stretch ing down the inclination of the surface over which the little flow de scends. Very often in my searchings I gathered little portions from various sites, sometimes very wet, sometimes, indeed, dried up by drought, and once only was I so fortunate as to find examples showing apothecia. I regret I have mislaid my rough drawing of the apothe cium itself, but fig. 1 is a sketch of the spores within an ascus. The general appearance of the apothecium, however, is like that of Sirosi phon. The asci were accompanied by linear paraphyses; the spores were four in an ascus, nearly colourless, broadly elliptic, simple, with two bright corpuscles, each with a minute dot in its centre immersed therein, one towards either end. Length of the spore, 3140", breadtb,

,'(figs. 1,2). Another S&ytonema, whose precise identity seems difficult to deter

mine, also presented apothecia. This too I found on only one occa sion; the contents usually formed a thin, somewhat irregular, central string up the middle of a somewvhat thick striated sheath, except near



ARCHER-On Apothecia in Alga. -

89

the apices of the " branches " (which sometimes were given off singly) in whieh they were thicker and quadratic (figs. 3-6). In this Scyto nema the nearly mature apothecia were globose, smooth, shining, of a dark brownish-chocolate colour, usually placed somewhere along the length of the filament, but might be occasionally terminal (figs. 3-6). Sometimes they seemed almost to form an interruption of the continu ity of the filament, or as if inserted into a special rounded excavation in it, and separated from it by a sharp line of demarcation (fig. 4).

Certain of the filaments showed here and there what seemed to be agglomerations of brownish-coloured granules, which by their quantity caused a distension of the filament and an interruption of the string of contents; these I took to be incipient apothecia, judging from their position; but this is of course not certain (figs. 9-11). The more mature apothecia seemed somewhat depressed at the top where the opening occurs (fig. 6). Like the apothecia of all these forms the present were very tough and intractable, the only plan to obtain the asci separate with their spores, on account of their minuteness, being to cause them to become ejected by (very forcible) pressure. In the present instance this was of more than usual difficulty, and I was un able to press out an ascus intact to discover if it was 4- or 8-spored; I believe, however, the latter. The paraphyses were slender, linear. The separated spores themselves were somewhat readily obtained, and they are different from the preceding, being much longer and nar rower, of lanceolate outline, simple, colourless, with a minute dot like corpuscle towards either end; length of spore, 4-i", breadth,

70(fi 8). Coming to S&roszphonaeea&, another case is offered by S. alpinu.

4Here the apothecia were smooth but not shiny, blackish, globular, variously situated, sometimes in the axil of a branch (fig. 13), some times along the length of the filament (fig. 12), or even terminal.

Here, as elsewhere, it was only by pressure that the asci and spores could be ejected. The asci, as elsewhere, at first filled with a grumous granular substance (figs. 16, 17), were, when mature, 8-spored (fig. 18). Sometimes I saw asci with the contents contracted to a broadly fusiform figure, and then divided transversely, thus pro ducing two conical bodies as if base to base (fig. 15). The para physes seemed to be of two lengths, the shorter about half the length of the asci, linear, pointed, the longer about one-half longer than the asci, nearly twice broader than the former, with truncate end (fig. 17). The spores here were different from either of the preceding, being uni septate, oblong, somewhat constricted at the middle opposite the sep tum, each end broadly rounded, colourless, each cavity showing a single central bright minute corpuscle; length, 1'1/ breadth, ' (fig. 14).

Another Sirosiphonaceous form, S. pulvinatus or S. Heufteri, showed apothecia. They appeared in a young condition to be hemispherical,

when mature, globose, sometimes as if somewhat produced upwards, and truncate at the opening (fig. 20). Unlike the previous, they did not appear smooth when young, but as if slightly hirsute externally



90 Proceedings of the Royal Irish Academny.

(fig. 19). The clavate asci sometimes appeared somewhat truncate (fig. 21); paraphyses very inconspicuous-indeed I am more inclined to think there were none; the asci were densely crowded. Many ex amples showed asci filled with granilar contents, the spores not yet formed. The asci when mature were 8-spored (fig. 22), the spores resembling in size and figure (but were very slightly longer than) those of the second form of Seytonema referred to, but they differed in not hav ing the two bright corpuscles immersed therein, and in showing a pale green colour. They were long andnarrow-lanceolate, greenish; length,

1560 , breadth, 'L/" (fig. 23).

The last form which rewarded my search in showing apothecia was the form recorded in " Flora Hibernica " as Stigone mamillosum, but the distinction which may exist between the plant in question and Stigonema mammiferum, Thwaites, or Sirosiphon coralloides, Xiitz., are not very apparent. Our plant grows in running water, attached to stones at the bottom of mountain streams. It is much more rare, seemingly, than any of the previous species, and is a very pretty plant under a moderate power of the microscope, especially a young and flourishing one, studded by the curious short and blunt branches, giving the " mamillate " appearance, with the phycoehromaceous con tents bright in colour. The apothecia resembled those in the Siro 8iphon above alluded to; they were blackish, globose (fig. 24); para physes linear, somewhat longer than the asci (fig. 25); spores four in an ascus, greenish, uniseptate, oblong, the septum appearing like a pale and hyaline slender transverse band, and somewhat constricted at the middle opposite the septum: thus the halves ovate, somewhat tapering to the bluntly-rounded ends, each cavity showing a bright corpuscle immersed in it; length, I ", breadth 4660L (fig. 26).

In all these forms I searched as well as I could for so-called sper mogonia, but was unable to detect any. These are comparatively so readily perceived in Ephebe (I myself found them before I was aware of Bornet's published account of them, or of the apothecia in that plant) that my non-success was the more disappointing.

Nor, after many trials by boiling in caustic potash, was I able to satisfy myself of the presence of hyphue, as can be so readily done in Epshebe, as first pointed out by Schwendener; there can, however, be little reasonable doubt but that they must exist, though the seeming nascent apothecia in the second form of S&ytonema referred to gave no indication of their presence; but that in itself would prove nothing, as the hypha cannot be seen in Ephebe without boiling in potash. Most probably my experiments were not conducted sufficiently long or care fully, for Boruet has showrn the existence of the hyphwe in his 1S3pilo nema paradoxum,4 and in his Liehenospheria Lenormandi.t

* Dr. E. Bornet : "

Description de Trois Lichens Nouveaux," in "

M?moires de la Soc. Imp. de Cherbourg," vol. iv., p. 225, t. i., ii.

f Dr. E. Bornet : " Recherches sur les Gonidies des Lichens," in

" Ann. des

Sei. Naturelles," 5 s?r., tome xvii., (of reprint, p. 57).



ARCHER- On Ajpothecia in Alyg. 91

But does it not appear somewhat inconsistent when Bornet, indescrib ing his Lichenosphceria Lenormandi, makes use of the follo wing language in the generic character:-'" Thallus tenellus, ramosus, fruticulosus, fere omnino stigonematoideus, basi corticatus; " and as descriptive of the specific characters-" Thallus fusco-niger, tomentoso-intricatus (altitudo vix 2 millim.), ramulis divaricatis subsecundis"? For, in fact, these words simply describe the thallus of Sirosiphon divaricatus,

Kiitz., which alga forms the host-plant for the peculiar lichenal para site in question. But when he goes on to describe the apothecia, the thecte, the spermogonia, the spores, he is giving the characters of the latter, which is the real " new species." In accordance with the new theory, besides the hyphue, this has no thallus of its own; the hyphte

merely push into the thallus of the Sirosiphwn, scarcely distorting it or causing any outward alteration, beyond the occasionally exserted apo thecia. If it were possible-and there is seemingly no great reason to the contrary-that the spores of this self-same Lichenosph'aria Lenor

mandi should afterwards grow upon and into another species of Sirosi phon, or, say even into a Scytonema, then some of the " specific charac ters" as given, nay, even probably some of the " generic," would disappear and others take their place. It is to be granted, indeed, that on the new theory, when a Nostoc becomes invaded by the parasite

which converts it into a Collema, a very considerable alteration is pro duced on even the outward aspect of the Nostoc; instead of a rounded, lobed, " blobby," and soft lump, it becomes more or less foliaceous, less watery, and more subdivided; but it is the alga all the time which submits to this alteration: the true lichen is ingide, only evincing itself externally by its apothecia and by its action on the alga (like a gall causing even greater modifications on a higher plant), inciting those changes of external aspect, whilst it is at the same time making use of the assimilating power of the alga to do for it what it cannot do by itself.

There can be little doubt buit that amongst these Scytonematous and Sirosiphonaceous alge quite distinct forms occur; but, on the other hand, there can be almost as little doubt but that Kiitzing has vastly over-enumerated them-that many of his so-called species are not dis tinguishable. Now, it is hard to conceive that one and the same para site would care very much which of forms so closely resembling it in vaded in order to pursue its course of life. Sirosiphon divaricatus seems not to differ much from S. alpinus; it is more fruticulose, the cells in the central stems seem to occur in more than double series:

what very perceptible barrier is there to the supposition that the pam site, which invades the former to form Lichenosphaeria Lenormandi,

Bornet, might not at another time invade the latter ? Would it not then fructify in the same way, show spores alike, &c. ? But the para site which does really invade the latter is not the same, as the figure herewith will show, not to speak of the paraphyses, so prominent a feature in the latter, being absent in Bornet's plant. Are these Scy tonemicolous and Sirosiphonicolous parasites, then, so extremely parti cular in their choice ?



92 Proceedings of the Royal Irish Academy.

See again the two Seytonemata, resembling in themselves so much and yet with " parasites" so distinct; the spores could not be con founded for a moment (see figs. 1, 2, and fig. 8). Again, see the great resemblance (but certainly not identity) between the spores in the second Scytonema and in Sirosiphon pulvinatws, algae mutually sufficiently unlike (see Figs 8 and 23).

It might again be asked whilst the new theory is, as it were, on its tral, at what period of the life of the Scytonema or Sirosiphon does it become invaded by the parasite ? At what part of the thallus does it make its entry ? It must be near the base, or at least not very high up, for the hypha is found growing pretty nearly pari pats with the growth of a branch of the alga, and in the same general direction. But what is to prevent the hypha growing in the opposite direction ? Might it not sometimes enter near the apex and grow backwards? Might we not expect sometimes to find hyphe stieking out from broken-up or distorted examples of these alg-e, and then revealing themselves (without the whole mass being boiled in potash) whilst on their way to invade other examples of quite the same alga? Or must the hypha appertaining to a particular plant have had its commence

ment from. a spore which found its way to and alighted somewhere ex ternally upon the particular Seytonema or Sirosiphon ?

The account given by Itzigsohn of Ephebella * is incomplete; he met with apothecia in his species of & Seytonema," containing asci, but they had not as yet developed spores. The plant he had in view may certainly be said to be quite distinct from Seytonema myochrous. It is probable the fructification would also have been seen, if fully mature, to have been also specifically different. So also are my two forms, both in thallus and fruetifieation. These, proceeding on the new theory,

would, perhaps, be relegated as " new lichens " to Eplhebella, Itzigsohn, or to Gonionema, Nylander; but neither is identical with Gonionemoa relutinum, Nyl. (of which I have seen examples in the late Admiral Jones's Herbarium), either as regards thallus or spores. The three other forms would probably be referred as "Inew species " to the "lichenous " genus Spilonema, or that referred to Sirosiphon puirinatus,

wanting paraphyses, might possibly be relegated to Liehenospherria. An experimental decision of the " gonidia-question," so far as it

relates to these Scytonematous and Sirosiphonaceous forms, is sur rounded by not a few practical difficulties. A sowing of spores upon the algae (as Reess did with N08toc) in a natural condition could only be carried out by an observer residing in or close to the subalpine situ ations where these plants flourish, as they could not be " cultivated " else

where. Lu order to obtain the spores he would further have, very probably, a troublesome preliminary search, and, on the other hand, there would hardly be a certainty of the plants selected for inoculation being themselves previously destitute of hyphae or apothecia. Of course small portions from various places in a tuft of any given alga could be

* Itzigsohn, in

" Hedwigia," 1857, p. 123.



ARCHER-On Apothecia in Alyw. 93

previously well examined, which, though if indeed found to represent the alga "I pure and simple," would not render it absolutely conclusive that some other portion of the tuft might not already have been invaded by the " parasite." However, having selected some plants for experi ment, they should be well inoculated with spores and portions removed from time to time for examination and experiment. If found satisfactory, it would be interesting to try to " cross " spores from the same and from diferent species (as, for instance, such as fig. 5 and fig. 26, or fig. 2 and fig. 19), in order to see the result, and whether the apparent fixity of the forms and the apparently extreme exclusiveness of the " parasites " be true or not, or ultimately whether the theory be true itself or not. Whether, for the time being, the truth of the new theory be previously assumed, or its untenability be presupposed, would

matter very little, if the suitable opportunity and ready field of opera tions were at command of the observer. It would seem as if in this

way only can either presupposition be justified or negatived. Pending the ultimate decision at w hich the great lichenists who

are at work on the broad question may arrive as to the true nature of these interesting plants, and pending, too, the discovery of the sper

mogonia of the forms here referred to, as assisting to throw a light on their mutual affinities and relative position, I may well leave to

more skilled hands the desultory notes brought forward in this com munication, touching their general bearing and ultimate application as regards one of the most interesting and problematic botanical ques tionsi of the day.

Rt. I. A. Proc., SER. II., VOt. II., c0



PLATE 6.

ILLrSTRATITE OF MR. ARCHER'S PAPER " ON APOTHECrA IN SOME SCYTO

NEMACECE AND SmROSIPrONACE."

Vide Proceedings R. I. Acad., Vol. 2, Ser. 2, p. 85.

Fig. 1. Ascus with 4 spores. 2. Single spore x 403.

From an unidentified Scytonema.

3, 4, 5. Apothecia. 6. Mature apothecium. 7. Same (in outline) burst, to show protruding asci and para

physes. 8. Spore x 400. 9-11. Showing internal agglomeration of brownish-coloured gra

nules causing swellings of the filaments (incipient apo thecia ?)

From Sirostphon e4pinu.

12. Fully formed apothecium. 13. Younger apothecium. 14. Spore x 400. 15. Ascus, immnature, with paraphyses, showing contents con

tracted into a fusiform figure and divided transversely. 16, 17. Immnature asci with paraphyses. 18. Showing portion of an apothecium burst so as to cause the

8-spored asci, with paraphyses, to become extruded (the rent portion of the apothecium not shaded).

From SirosIhon pulvinatus or S. ieufteri.

19. Imrnature apothecium. 20. Outline of mature apothecium. 21. Immature asci. 22. Mature ascus with .8 spores. 23. Spore x 400.

From Stigonema manlilosum.

24. Apothecium. 25. Immature asci with paraphyses. 26. Spore x 400.

R. I. A. PROC., SER. II.T VOL. II., SCIENCE. b



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Article Contentsp. 85p. 86p. 87p. 88p. 89p. 90p. 91p. 92p. 93[unnumbered][unnumbered]

Issue Table of ContentsProceedings of the Royal Irish Academy. Science, Vol. 2 (1875 - 1877), pp. i-viii, 1-760, 1-26, i-clivFront MatterOn Heat as a Factor in Vital Action (So Called) [pp. 1-6]On Changes in the Physical Geography of Ireland [pp. 6-22]On a Cause of the Buoyancy of Bodies of a Greater Density than Water [pp. 22-25]On Some General Formul for the Solution of Algebraical Equations of the Third Degree, &c. [pp. 26-39]On the Equation of the Squares of the Differences of a Biquadratic [pp. 40-41]On a Spectroscope of the Binocular Form for the Observation of Faint Spectra [pp. 42-45]On Fossils from the Upper Old Red Sandstone of Kiltorcan Hill, in the County of Kilkenny. Report No. 1 [pp. 45-48]Notes on the Myology of the Coati-Mondi (Nasua narica and N. fusca) and Common Martin (Martes foina) [pp. 48-55]On Some Points in Bird Myology [pp. 56-58]The Presence of a Lachrymo-Jugal Suture in a Human Skull, and on Its Comparative Anatomy [pp. 58-61]On Two New Species of Pentastoma [pp. 62-66]On the Muscular Anatomy of Cholpus Didactylus [pp. 66-78]On Retro-Peritoneal Cavities [pp. 79-80]Laboratory Notes [pp. 81-84]On Apothecia Occurring in Some Scytonematous and Sirosiphonaceous Alg, in Addition to Those Previously Known [pp. 85-93]Microscopical Structure of Rocks. Report No. I. Ingenite Rocks [pp. 94-101]Granitic and Other Ingenite Rocks of Yar-Connaught, and the Lower Owle; Or the Mountainous Tract of Country West of Loughs Mask and Corrib [pp. 102-138]On a Few Points in the Cranial Osteology of Sloths [pp. 139-139]On Chlamydomyxa labyrinthuloides, nov. gen. et sp., a New Freshwater Sarcodic Organism [pp. 140-159]List of Seychelles Myrtace, with Descriptions of Two New Species [pp. 160-160]Report on the Microscopical Structure of Rocks. No. 2 [pp. 161-163]Report on the Microscopical Structure of Rocks. No. 3 [pp. 164-165]On Some Further Improvements of the Comparable Self-Registering Hygrometer [pp. 166-167]On Two New Deposits of Human and Other Bones, Discovered in the Cave of Dunmore, Co. Kilkenny [pp. 168-176]On a Fossil Saurian Vertebra, Arctosaurus Osborni, from the Arctic Regions [pp. 177-179]Ingenite Rocks. Report No. 4 [pp. 180-182]On Some Newly Observed Properties Possessed by Certain Salts of Fulminic Acid [pp. 183-188]On the Constituents of the Two Principal Mineral Waters of Lisdoonvarna, County of Clare [pp. 189-192]On the Ligamentum Mucosum [pp. 193-201]On Some Forms of the Ligamentum Pterygo-Spinosum [pp. 202-205]On a Malformed Corona of Echinus esculentus [pp. 206-208]Remarks on the Structure of the Leaves of Certain Conifer [pp. 209-213]On Two Dissimilar Forms of Perityphlic Pouches [pp. 214-217]Note on the Spectrum, Polarization, and Form of the Zodiacal Light; As Observed in the Years 1874 and 1875 [pp. 218-224]On a Ready Means of Detecting Arsenical Compounds [pp. 225-229]Further Researches on the Dissociation of Molecules in Solution [pp. 230-234]Report on the Irish Diatomace: Part I [pp. 235-425]Notes on Some Anomalies in the Course of Nerves in Man [p. 426-426]On the Theory of the Cup Anemometer, and the Determination of Its Constants [pp. 427-442]The Drifting Power of Tidal Currents versus That of Windwaves [pp. 443-458]An Estimation of the Free and Albuminoid Ammonia Yielded by the Stagnant Waters of the Dublin Streets, as Compared with the Quantities of Those Substances Obtained from the Liffey Water, after Receiving the Sewage [pp. 459-462]On an Elementary Proof of "Lagrange's Equations of Motion in Generalized Co-ordinates" [pp. 463-464]On the Exploration of the Knockninny Cave. With an Account of the Animal Remains [pp. 465-483]On Personal Errors in Astronomical Transit Observations [pp. 484-528]Analysis of Coals and Iron-Stones from the Dungannon Coal-Field, Co. Tyrone [pp. 529-538]On a Case of Polydactylism [pp. 539-546]Report on the Exploration of Ballybetagh Bog [pp. 547-552]Report on the Flora of Inish-Bofin, Galway [pp. 553-578]On a New Chemical Test for Alcohol [pp. 579-582]On a New Genus and Species Belonging to the Family Pandarina [pp. 583-585]Notes on a Small Collection of Foraminifera from the Seychelles [pp. 586-588]On Some Foraminifera from the Loo Choo Islands [pp. 589-590]Report on Irish Hepatic [pp. 591-672]A Revision of the Species of Abies [pp. 673-704]A Contribution to the History of Dolomite. The Dolomites of the Carboniferous Limestone of Ireland [pp. 705-730]Reports from the Chemical Laboratory of Trinity College, Dublin: No. 1. On Glucinum: Its Atomic Weight and Specific Heat [pp. 731-735]On the Chemical Changes Which Take Place in the Potato during the Progress of the Disease [pp. 736-737]Remarks on the Recent Discovery of Remains of the Cervus Megaceros at Ballybetagh [pp. 738-741]The Detection and Precipitation of Phosphoric Acid by Ammonic Molybdate [pp. 742-743]On a Certain Relation between the Quadratic Expression , and the Product of the Squares of the Differences of the Roots of a Cubic Equation [pp. 744-753]On a New Genus and Species of Sponge [pp. 754-756]Index to Volume II of the Proceedings [pp. 757-760]Royal Irish Academy. Minutes of Proceedings [pp. i-cliii]General Abstract of the Account of John Ribton Garstin, Treasurer of the Royal Irish Academy, for the Year Ending 31st of March, 1876 [pp. cliv-cliv]

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On Apothecia Occurring in Some Scytonematous and Sirosiphonaceous Algæ, in Addition to Those Previously Known