22 NATURAL HISTORY SOCIETY OF DUBLIU. 



or Mesotsenium — into or from any other plant, is by no means so conclu- 

 sive as regards an actual diamorphosis, as are De Bary's observations on 

 their development from one generation to another, through germination 

 of the spore formed by conjugation, apparently decisive as regards their 

 perpetuated identity and constancy. Kutzing, indeed, speaks of a tran- 

 sition of his P . protulerans into a Scytonema,* and of his P. vesiculosa 

 into a Zygogonium ; but, very deferentially, I think his statements and 

 figures are too meagre, in these cases, to prevent great doubt as to the 

 correctness of his conclusions ; besides, it is possible, indeed, that his 

 plants thus called may not, strictly speaking, belong at all here. 

 Again, Dr. Hicksf draws attention to an elongate form of cell noticed 

 by him during the development of Lichen-gonidia, and which he con- 

 siders nothing but a "Palmoglcea;" consequently, he seems to come to 

 the conclusion that all the Palmoglcea-forms are but conditions in the 

 growth of the gonidia of Lichens. Far be it from me to doubt the ac- 

 curacy of Dr. Hicks' very valuable and remarkable observations ; but, 

 at least, so far as the forms of Cylindrocystis and Mesotaeniuni (by 

 whatever names they may pass) are concerned, I would suggestively 

 put it, that here as elsewhere, resemblance may by no means necessarily 

 constitute identity. We are not now so much astonished as formerly at 

 remarkable cases of homomorphism, even in organisms very high in the 

 scale, and well know that such sometimes do not indicate even any 

 affinity, not to speak of identity. And I should certainly be disposed 

 to imagine that homomorphs are not less likely to occur in such simple 

 plants as those under consideration, than in regard to the more compli- 

 cated and elaborate organs of higher existences, even in animal life. 

 Dr. Hicksf speaks of "large oval cells precisely similar to Palmogloea" 

 (Kutz.) (Cylindrocystis, Menegh.,Coccochloris, Hass.), as occurring dur- 

 ing the development of certain Lichen-gonidia ; and he considers the oval 

 cells represented in his figure§ as "visually identical" with "Palmogloea 

 Brebissonii." If he means by this, Palmogloea Brelissonii (Kiitz.), 

 which Kiitzing makes out to be identical with Palmella cylindrospora 

 (Breb.), which latter Ealfs considers identical with his Penium Brelis- 

 sonii, then I am bound to say I cannot agree that Dr. Hicks' form is by 

 any means " visually identical" with that indicated by the names just 

 quoted. That alluded to {Penium Brelissonii, Balfs), is undoubtedly 

 a Cylindrocystis, and Hicks' figure suggests to one more the idea of a 

 Mesotsenium with the broad side of the chlorophyll-plate uppermost, 

 but does not at all call to mind a species of the former genus. If it be 

 assumed as presenting a form of Mesotaenium, the granular endochrome, 

 which so often obscures the view of the chlorophyll-plate, seems to be 

 very deficient, for the central corpuscle is to be seen in all the cells 

 figured. This central corpuscle is regarded by Hicks as a nucleus ; it 



* "Phycologia Generalis," p. 178. 



t " Quarterly Journal of Microscopical Science," vol. ii , N. S., pp. 17 and 20. 



j Loc. cit., p. 17. § lb., PL II., Figs. 11, 12. 



