THE PHYSIOLOGY OF SECRETION. 167 



carbonic anhydride and ammonium lactate. Just how the fats 

 escape from such cells as those of adipose tissue is unknown, 

 but from analogy with the process of absorption of fats, it is 

 not impossible that they are first saponified or broken into 

 soluble glycerines and soaps. Even the ferments appear to be 

 formed in the same manner. They exist normally in the cell in 

 a much less soluble form, and are apparently broken up into 

 active ferment fragments only at the time of secretion. Be- 

 sides these cases in which the fragments are small enough to 

 be removed by osmosis, there is hardly a doubt that in all gland 

 cells this process of splitting up complex molecules into simpler 

 ones precedes secretion, even if the process does not normally 

 go far enough to produce an osmosable product. This process 

 of decomposition increases the number of soluble molecules in 

 the cell, and increases thereby its osmotic equivalent. The 

 cell, in consequence, grows by the absorption of water and 

 takes on the swollen appearance of many so-called loaded gland 

 cells. This incidental result of increased cellular turgor is 



O 



utilized, as we shall see, in certain processes of secretion. 



The second manner in which these complex substances may 

 be eliminated from the cell is by the budding off of a portion 

 of the cell containing them. Actinophrys not infrequently 

 detaches small portions of its protoplasm, which crawl about 

 for a time but ultimately go to pieces. This is a true process 

 of secretion. The excretophores of leeches, according to Graf, 

 undergo a similar process. The cells loaded with secretory 

 products approach the funnels of the nephridia and portions of 

 them gradually break off, disintegrate, and the debris is swept 

 out of the body. We might call this secretion by budding. 

 Secretion here passes by a simple gradation into cell division, 

 the sole difference being that in such secretion the bud does 

 not contain a nucleus, and, in consequence, the budded off por- 

 tion soon goes to the ground. But even this is not a hard-and- 

 fast line of demarcation, because in many instances of cell 

 division the cells budded off, even though containing a nucleus, 

 undergo degeneration and are converted into a so-called secre- 

 tory product. Such cases occur, for example, in the mucous 

 glands of the skin of Petromyzon, in which the cells thus budded 



