THE SECRETORY TISSUES AND ORGANS. 289 



afterwards dissolved and sent in solution to nourish the 

 young plant. 



Gland-cells might a priori give rise to the specific ele- 

 ments of secretions in either of these ways, and we have to 

 seek in which manner they work. Do they simply act as fer- 

 ments (however that is) upon the surrounding medium; or 

 do they form or collect the bodies characterizing their 

 secretion, first within their own substance, and then liberate 

 them, either disintegrating or not at the same time ? At 

 present there is a large and an increasing mass of evidence 

 in favor of the second view. There is, no doubt, some 

 reason to believe that every living cell can act more or 

 less as a ferment upon certain solutions should they come 

 into contact with it. Not always, of course, as an alcoholic 

 ferment, though even as regards that one fermentative power 

 it seems very generally possessed by vegetable cells, and there 

 is some evidence that alcohol is normally produced in small 

 amount (and presumably by the fermentation of sugar) under 

 the influence of certain of the living tissues of the Human 

 Body. As regards distinctively secretory cells, however, the 

 evidence is all the other way, and in many cases we can see 

 the specific element collecting in the gland-cells before it is 

 set free in the secretion. For example, in the oil-glands of 

 the skin (Chapter XXVIII) we find the secreting cells, at 

 first granular, nucleated, and protoplasmic, gradually under- 

 going changes by which their protoplasm disappears and is 

 replaced by oil-droplets, until finally the whole cell falls to 

 bits and its detritus forms the secretion; the cells being re- 

 placed by new ones constantly formed within the gland. In 

 such cases the secretion is the ultimate product of the cell- 

 life ? the result of degenerative changes of old age occurring 

 in it. 



In other cases, however, the liberation of the specific ele- 

 ment is not attended with the destruction of the secreting 

 cell; as an example we may take the pancreas, which is a 

 large gland lying in the abdomen and forming a secretion 

 used in digestion. Among others, this secretion possesses 

 the power, under certain conditions, of dissolving proteids 

 and converting them into dialyzable peptones (p. 10). This 

 it owes to a specific element known as trypsin, the formation 

 of which, or rather of its forerunner trypsinoyen, within the 

 gland-cells can be traced with the microscope. 



