Dr Barry on Fissipc^ous Generation. 207 



discerned ; and, secondly, that cells in general present a cor- 

 responding orifice in the centre of the nucleus, as if provided 

 for the introduction of the substance to be so assimilated. * 



6. I conceive that what is seen taking place in the manner 

 here referred to, — first in the germinal vesicle, and then in the 

 individual cells, the descendants of this vesicle, — is not un- 

 connected with what we observe in the reproduction of the 

 entire organism — namely, a mysterious re-appearance of the 

 qualities of both parents in the offspring, manifesting itself, 

 as this re-appearance does, in the assemblage and metamor- 

 phoses of the cells.t 



7. I have thus referred somewhat minutely to facts which 

 I had previously mentioned, for the purpose of shewing that 

 they may assist to explain a process described in the foregoing 

 paper. \ There, as well as in one of my former memoirs, cer- 

 tain nuclei are delineated as contained within and among the 

 fibres of tissues. § Corresponding nuclei have been seen, 

 figured, and described by others ; and it has been conjectured 

 that they are the source of new substance ; but the office 

 which, more particularly, these nuclei perform, appears not to 

 have been explained. I conceive them to be centres of assi- 

 milation ; having been led to this opinion by observing, in the 

 first place, that they present the remarkable orifice in ques-: 

 tion ; and, secondly, that they are reproduced by self-division. 

 They descend in this manner from the nuclei of the original 



* That part of the nucleus to which the orifice leads, is the part where there 

 is a continual origin of finely granular substance. (See my *^ Researches in 

 Embryology, Third Series," Phil. Trans., 1840, p. 549, par. 385 ; and the de- 

 scription of figs. 43 and 45, in my paper " On the Corpuscles of the Blood, Part 

 II.," Phil. Trans., 1841.) The fact, too, that nuclei are found for a while at 

 the surface of their cells, suggests the idea that they may remain there for a 

 purpose analogous to that for which the germinal spot continues, up to a cer- 

 tain period, at the surface of its vesicle in the ovum. 



t Cells, according to my observations, being propagated by division of their 

 nuclei, it appears to me, that, in reality, there is but one mode of reproduction — 

 namely, the fissiparous — for what is called the highest organism, even after fe- 

 cundation, is originally a simple cell. 



X See the introductory paragraph. 



§ Phil. Trans. 1 842, PI. vi. figs. 22, 23; PI. vii. figs. 35, 39, 42-44, 57 ; PI. viii. 

 figs. G8; PI. X. figs. 130, 132, 133-137 ; PI. xi. figs. 155. PhU. Trans. 1841, 

 PI. xxiii. figs. 135-137 ; PI. xxv. figs. 157-159. 



