48 ORGANISMS OF ONE CELL 



the first stages of protoplasm re-building and many more steps 

 must be taken before the essential elements are added to the 

 protoplasmic molecules. These further steps are generally 

 included under the comprehensive term assimilation and their 

 exact nature is hidden in the deepest obscurity. Little by little 

 chemical research is throwing light on the processes so that we 

 have now a basis for working hypotheses as to the manner in 

 which protoplasmic molecules are built up. We now know that 

 cells in all kinds of tissues possess chemical properties hitherto 

 unsuspected. These have to do, in the main, with enzymes 

 which act upon the partially broken down food matters and 

 cause their disintegration into finer particles until they are 

 prepared for anchorage in the protoplasmic molecules and begin 

 the series of integrations and disintegrations characteristic of 

 vital processes. It has been found by experiment that portions 

 of the cell without a nucleus cannot form such enzymes and the 

 conclusion is drawn that these vital activities are dependent 

 upon substances derived from the chromatin. It was largely 

 through experiments in cutting minute forms like Amoeba that 

 this discovery was made. Nusbaum, Hofer, Verworn and 

 others found that if an amoeba is cut in two pieces with a scalpel, 

 both parts would continue to live for some days but one would 

 die ultimately while the other part, containing a nucleus would 

 continue to live and multiply indefinitely. The portion with- 

 out a nucleus is unable to digest and assimilate food, or even to 

 capture it. 



Thus while the exact processes of assimilation are unknown 

 in amoeba it is quite probable that the finer changes are carried 

 on in the same way as with cells in higher animals, that is 

 through the agency of enzymes. These act in a linked series 

 the product of one chemical action furnishing the material for 

 the next until finally the elements derived from the proteid food 

 are added to the protoplasmic moleculesxj^ 



Knowledge of the anabolic or building processes is much more 

 hypothetical than that in regard to the katabolic or breaking 

 down processes the latter taking place whenever energy is 

 expended. These processes take place in the cell body or cyto- 



