Dr Barry on Fissiparous Generation. 215 



pearances presented by the mammiferous germ during the 

 passage of the ovum through the oviduct, and those met with 

 in the young Volvox globator while within the [parent, I find 

 a resemblance which is very remarkable indeed, extending 

 even to minute details. Not only do the cells of which the 

 young Volvoz is composed form a body resembUng a mulberry 

 (fig. 8, d.), with a pellucid centre, but the cells gradually 

 increase in number apparently by doubling, and at the same 

 time diminish in their size, like the cells of the mammiferous 

 germ, which they resemble also in being originally elliptical 

 and flat ((3, y). 



54. Some of the points of resemblance now mentioned, I 

 recognised in the delineations of the Volvox given by Pro- 

 fessor Ehrenberg ;* others were noticed during some observa- 

 tions I have myself made on this very interesting microscopic 

 object. 



55. Ehrenberg has figured five pellucid globules in a young 

 Volvox just escaped from the parent. t These, the germs of 

 another generation, evidently resulted from division of the 

 pellucid mass (the hyaline) visible in an earlier state (fig. 8. «) ; 

 so that here is to be recognised fissiparous generation of the 

 kind I have described as reproducing cells. 



56. On comparing the figures given by Ehrenberg of succes- 

 sive generations of the Chlamidomonas (fig. 4), with the suc- 

 cessive groups of cells (two, four, eight, &c.) in the mammife- 

 rous ovum,J I cannot help believing that the process of for- 

 mation is the same in both ; the essential part of this process 



gradations of this spontaneous division of the organized contents of the integu- 

 ment in the Gonium and Chlamydomonas, which may be compared with the 

 earliest stages of the development of the germ, as figured by Siebold in the 

 Strongylm and Medma, by Baer in the Frog, and by Barry in the Rabbit. Dr 

 Martin Barry, who has discovered the very remarkable and complicated nature 

 of this process in the mammalian ovum, was alone perhaps in the condition to fully 

 comprehend and explain its analogy to the fissiparous generation of the polygas- 

 tria, to which, in 1840, I briefly alluded ; and this he has done in a paper re- 

 plete with interesting generalisations, lately read before the Royal Society." 

 Hunterian Lectures. By Professor Owen, F.B.S., from notes taken by W. W, 

 Cooper, M.B. C.S., 1843. The paper here referred to by Professor Owen, is that 

 of which the present communication is a pai-t.] 



* Die Infusionsthierchen als volkommene Organismen. Leipzig, 1838. 



t Loc. at. Tab. iv. Fig. I. 2. 



\ Researches in Embryology, rhil. Trans. 1830 and 1840. 



