208 Dr Barry on Fissiparous Generation. 



cells of development ;* 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.j But what 

 I wish to add is, that the origin of new filaments in these nu- 

 clei appears to me to have especial reference to that assimila- 

 tion of which they seem to be the centres. 



8. Although every nucleus seems to possess a reproductive 

 property, there are thus special centres of reproduction. Such 

 centres were also particulai'ly indicated in one of my former 

 memoirs,^ as existing in the epithelium, the pigraentum ni- 

 grum, " cellular" tissue, and cartilage. In describing the 

 first origin of muscle, nerve, and the crystalline lens, also, I 

 directed attention to such centres, stating that we might here- 

 after see reason for thinking it not unimportant that the con- 

 tents of the " primitive" cell, and those of the " secondary" 

 cylinder, should have their origin in the nucleus ; and I was 

 particularly desirous of connecting this fact with the existence 

 of the orifice in question. It will now be seen that I had in 

 view the subject of assimilation now referred to.§ 



9. Such, then, were my views long since.|| They remain 

 unaltered ; and I have the satisfaction of recognising a con- 

 firmation of them in the views just published by Dr Carpenter, 

 which to me are the more valuable from his having formed 

 them without any knowledge of my own. 



10. Dr Carpenter directs attention to the large number of 

 transitory cells which I had shewn in each instance to form a 

 sort of pabulum for the central ones, and most justly adds, 

 " Is it to be supposed that all this cell-life comes into exist- 

 ence without some decided purpose V^ He considers that 

 " the conversion of the chemical compound into the organizable 



* They are not in advanced stages, as it has been said, the nuclei themselves 

 of these cells. And it is a mistake to suppose them fresh " deposits," which, 

 however, has been done. 



t Phil. Trans. 1842, PI. xi. fig. 155. Ibid, 1841, PI. xxii. figs. 110-116. 



X Phil. Trans. 1841, pars. 119, 120, 135, 144. 



§ Phil. Trans. 1841, par. 162. 



II It will be seen from the preceding paragraphs that they were essentially the 

 same in June 1841. 



T British and Foreign Medical Review, No. XXIX., Jan. 1. 184.3, p. 270. 



