NA TURE OF SECRETION. 2 o I 



modified and are about to eliminate. In short, the 

 gland cell is supposed to take up certain matters as 

 cells in general take up nutrient materials to grow, 

 to pass through certain phases of existence, and to 

 die, its contents being set free at the time of its 

 destruction. The place of this cell is then occupied 

 by a new one which grows up. If this view is correct, 

 it follows that numerous cells in every gland must 

 grow, pass through their several stages of existence, 

 and die in the course of a few hours at most ; and 

 necessarily the changes occurring in the cell must 

 take place very quickly indeed. 



Now what are the facts which lead us to conclude 

 that in the ordinary process of secretion the cells are 

 thus destroyed bodily ? It is indeed quite true that 

 cells occupying different positions in a gland follicle 

 exhibit different characters, the most mature cells 

 apparently containing the perfectly elaborated secre- 

 tion. But does this fact alone prove that these cells 

 are removed and renewed as fast as the secretion is 

 formed ? Can the fact be only explained upon such 

 a view ? There is no doubt that the epithelial cells 

 are gradually cast off bodily from the surface of 

 the cuticle and mucous membranes and replaced by 

 new ones, which grow up from below ; and this is an 

 argument in favour of the occurrence of a similar pro- 

 cess in glandular organs, but the analogy has surely 

 been much overstrained. The rate of desquamation 

 of cuticular epithelium for example is not very rapid, 



