110 .NATURE OF PROTEOLYTIC FERMENTS 



such a structure, that the decomposition can be 

 effected by means of the ferments it possesses. A 

 breach is made into the cell-wall ; its contents are laid 

 bare, and can then be utilized as nutriment. 



This unicellular organism shows us, then, that 

 the various alga? have a very different cell structure. 

 The defensive ferments prove the same thing, and 

 provide us with knowledge which we should be 

 unable at present to arrive at by any other means. 



Exhaustive researches are now in progress, which 

 seek to ascertain whether the separate kinds of cells 

 of an organism have the command of specifically 

 directed ferments. We know that every cell requires 

 ferments for the purpose of breaking up the food that 

 is brought to it, or of constructing new compounds 

 out of it. Further, we know that the cell is able to 

 disintegrate parts of its own contents, and to replace 

 them by new material. Is it not probable that 

 specific activities are indicated in this case also ? In 

 the course of our experiments in this direction pep- 

 tones were produced from certain cells, and the 

 decomposition of these peptones by the correspond- 

 ing cell ferments was then attempted. As a matter 

 of fact, juices obtained from certain organs by 

 extraction or maceration decomposed only peptones 

 or albumen from the corresponding tissues ; that is 

 to say, extracted thyroid juice broke down peptones 

 obtained from that organ, but not liver peptones 



