Nucleus of the Animal and Vegetable " Celiy 213 



Descending, as cells thus do, from an original mother-cell, 

 and this by cleavage of the nucleus of that mother-cell, and 

 all subsequent nuclei being propagated in the same way, 

 by fissiparous generation, — such being the process, every nu- 

 cleus or particle of hyaline is a sort of centre, inheriting more 

 or less of the properties of the original nucleus, the germinal 

 spot of the fecundated ovum ; and exercising an assimilative 

 power. (The corpuscles of the blood are floating centres of 

 assimilation.) 



I wish it to be distinctly understood, that, in my researches, 

 I always endeavoured to keep strictly to observation, avoid- 

 ing all theory ; and it may be here remarked, that some of 

 tliose on the divisions in the ovum, just referred to, were 

 made before I knew much of cells. Of one kind of animal 

 alone, the Rabbit, about 150 were sacrificed in these obser- 

 vations ; some of the most important of which I had the op- 

 portunity of enabling my honoured friend Professor Owen to 

 confirm, by submitting the objects under the microscope to 

 his practised and most rigorously scrutinizing eye. 



How satisfactory now to find my observations confirmed by 

 researches subsequently made by others. Thus the younger 

 of the brothers Goodsir has since found, in the ovum of a 

 cystic entozoon,* the»germinal vesicle to fill with cells from 

 the germinal spot, by a process obviously the same as that 

 wliich I had described in the ovum of the Mammal ; the 

 germinal vesicle enlarging so as to occupy the entire ovum. 

 Compare in Plate I., figs. 45 and 46 ; and read the descrip- 

 tion of the latter figure. 



Farther, how satisfactory now to find those observations 

 of mine adopted and formally applied in various departments 



to that of the elliptical disc, and, of course, quite as general ; viz., the globular, 

 for every disc (cytoblast) appears to have once been a pellucid globule of hya- 

 line. — No observer can learn the structure of the blood-corpuscles, who does 

 not carefully investigate their mode of origin ; and this, not in blood taken 

 from large vessels, which are merely channels for conveying it, but in that con- 

 tained, and almost at rest, in the capillaries, and especially in the capillary 

 plexuses and dilatations. 



* Caenurva cerebralis. Trans. Royal Society, Edinburgh. 1844. Vol. xv., 

 PI. xvi. 



