Nucleus of the Animql and Vegetable ^^Cell*'' 219 



written, or he would not have supposed the secretion con- 

 tained in the cell-cavity to be produced by the ceW-wall ; for 

 in a subsequent paper, in which he attributes the property 

 of secretion to the nucleus of the cell, he acknowledges it to 

 have been my observations " on the function of the nucleus in 

 cellular development'^ that convinced him he had been in error 

 in attributing that property to the cell-wa//. So minutely 

 had the mode of origin of the red colouring matter and that 

 of the pigmentum nigrum been investigated by me, that I had 

 found, in the first place, the red colouring matter to be formed 

 by the hyaline nucleus of the cell ; and, secondly, that red 

 colouring matter to afford a medium for the formation of the 

 black pigment, which also was seen to arise out of the hya- 

 line nucleus within the cavity of the cell. 



As all the tissues have their origin in corpuscles present- 

 ing the same colour, form, and size, as corpuscles of the 

 blood, — and if all cells are derived, as I believe them to be, 

 from the corpuscles of the blood, — it will be seen that the 

 red colouring matter is a secretion of importance, and this 

 on two accounts. In the first place, it is universal, — for every- 

 where, in greater or less quantity, it is reproduced ; and se- 

 condly, it no doubt aifords a medium for the formation of 

 other substances in the cell-cavity, as well as for that of the 

 pigmentum nigrum. It corresponds in fact to the finely gra- 

 nular substance of every nucleus and cytoMast, which comes 

 into vietp as new matter is appropriated by the hyaline. 



I obsei've confirmations in other quarters also. Some of 

 these were referred to on former occa- pj 28 29 30 31. 

 sions,* and need not be particularly men- 

 tioned here. They are, Schwann's deli- 

 neations of the cells of cartilage, figures 

 by Valentin of ganglion-globules, and 

 drawings by Miiller of the cells of morbid 

 growths. Figs. 28, 29, 30, and 31, since 

 published by Dr Bagge,t represent stages 

 of the ovum of an intestinal worm ; con- 



* Phil. Trans., 1840, p. 552, note. 1841, pp. 207, 208. 

 t De Evolutione Strongyli, &c. 4to. 1841. 



