312 IV. THE PRINCIPLES OF LIFE PHENOMENA 



Various denaturating agents involved in blood coagulation may be 

 called enzymes in a wide sense. However, since it has been found 

 that thromboplastin reacts with prothrombin in stoichiometric amounts 

 (156), at least thromboplastin cannot be regarded as an enzyme in a 

 narrow sense. On the other hand, it has been claimed that thrombin 

 is not involved in the coagulation of the fibrinogen molecules, indicat- 

 ing that thrombin acts as a true enzyme, because a protein which can 

 disturb the structure of another protein and which is not consumed 

 in this reaction should be termed a true enzyme. Nevertheless, the 

 fact that papain clots fibrinogen just as thrombin does is not sufficient 

 to prove the enzyme nature of thrombin (157). Trypsin is also known 

 to be able to convert prothrombin into thrombin. These enzymes may 

 act only to disturb the structure of the protein as do the blood clotting 

 agents such as thromboplastin and thrombin. 



At any rate, blood coagulation may be regarded as a chain reaction 

 brought about by a series of enzymes in a wide sense. The concept 

 that a protein having a stronger structural influence overcomes a weak- 

 er by disturding the structure of the weaker, or, in a particular case, 

 by converting the structure of the weaker to be identical with that 

 of the stronger, has led the writer to the theory of enzyme function 

 and further of the mechanism of the generation of life. It may be 

 considered that life phenomena are based upon the combination of 

 various kinds of proteins, that possess this fundamental property, 

 joining together orderly as in this case of blood coagulation for a 

 definite purpose in making an "enzyme system". 



Presumably, enzyme systems present in living organisms are not 

 necessarily composed of enzymes in a narrow sense. Protein molecules 

 which can act as true enzymes may be rather exceptional, mostly 

 behaving as enzymes in a broad sense as does thromboplastin in the 

 blood coagulation. 



5. The Mechanism of Mitosis. 



In case of the cell division, the nuclear substances capable of 

 determining the inheritable character are divided into two equal parts, 

 each of which are subsequently distributed to daughter cells, by an 

 apparently very complicated process termed mitosis. Though this pro- 

 cess appears very mazy, since it is a basic phenomenon generally 

 taking place in orgnisms, it must be a process raised by some simple, 

 fundamental properties of protoplasm. 



In the writer's opinion, as described in Part II, the protoplasm is 

 composed of polypeptide chains, which make up elementary bodies in 



