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 algæ 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 peptones were produced from certain cells, and the decomposition of these peptones by the corresponding 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
