Nucleus of the Animal and Vegetable " Cell.'*^ 215 



cells. I said, " It will be remarkable if the mammiferous 

 ovum, which, because of its minuteness and the difficulty of 

 obtaining it, had been considered beyond the reach of satis- 

 factory observation, should now become the means of study- 

 ing, not merely other ova, but certain processes by which 

 nourishment is communicated, and the growth of the body 

 effected at all future periods of life. Such, however, I think 

 will really be the case." 



As affording probability that this anticipation would be 

 realized, I figured centres, special centres ^ of reproduction and 

 assimilation ; directing attention more particularly to such 

 centres as were situated in the walls of tubes, — as, for in- 

 stance, in those 



entering into the '^' 



formation of mus- 

 cle (fig. 26), the 

 crystalline lens 

 (fig. 27), and 

 nerve : on which 

 Iremarked,""We 

 may hereafter see 



reason for thinking it not unimportant 

 that the contents of the ' primitive** cell 

 and those of the * secondary* cylinder 

 should have their origin in the nucleus.""* 

 And subsequently, when those centres 

 were referred to, my views regarding 

 them were stated in the following words : 

 — " I conceive them to be centres of assimilation ; having been 

 led to this opinion by observing, in the first place, that they 

 present the remarkable orifice in question ; and, secondly, 

 that they are reproduced by self-division. They descend in 

 this manner from the nuclei of the original cells of develop- 

 ment, i.e. from the nuclei of the corpuscles of the blood. 

 That they are the source of new substance is very obvious ; 

 for they may be seen either unwinding into a filament, or 

 becoming spindle-shaped to form one. But what I wish to 



Fig. 27. 



* Phil. Trans., 1841, p. 236. 



