276 THE PHYSIOLOGY OF REPRODUCTION 



investigations as to the presence or absence of a particular 

 constituent have not been made. 



With regard to the question of the presence of ferments and 

 their significance we are on very difficult ground. We must 

 here clearly distinguish between endo-enzymes and secreted 

 enzymes. The endo-enzymes comprise all those enzymes which 

 are so closely bound up with the protoplasm that they can be 

 isolated only after the cell has been destroyed. Their sphere of 

 activity is therefore limited to the inside of the cell. Such 

 endo-enzymes are present in every organ, and have also been 

 found in the egg,^ producing proteolysis and lipolysis. But since 

 such endo-enzymes are present in many, if not in all ceUs, no 

 special significance can be attached to their presence in the eggs. 



The presence in the egg of secreted ferments analogous 



to the ferments which can be obtained by simple extraction 



from the digestive glands of the adult animal, would allow 



of more definite conclusions. The presence of such ferments 



1 Wohlgemuth, " Uber das Vorkommen von Fermenteu im Hiihnerei," 

 Fentsohrifl filr Salkowaki, 1904. 



