118 II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



antigen, provides likewise an evidence that the force arising from tlie 

 specific arrangement of polar groups may increase in the direct pro- 

 portion to the degree of polymerization. It is known that the number 

 of antibody molecules combining with the antigen increases as the 

 latter molecule increases in size, and it is also accepted that both 

 enzymes and antigens have to be in colloidal states in order to exert 

 their action ; in all these facts seems to be involved the force coming 

 from the polymerization. The peculiar property of colloid may also 

 be closely connected with the same force. 



The fact that viruses are the particles of more than certain 

 sizes may indicate the necessity of polymerization of virus proteins 

 to a certain degree for the development of the activity. 



If the protoplasm is disintegrated into its elementary bodies, and 

 if in the bodies the original structure of the protoplasm is retained, 

 the bodies themselves also can act as an assimilase. Viruses are 

 regarded as a kind of the assimilase existing in such minute bodies. 



However, the assimilase, when present in the form of free ele- 

 mentary bodies, is much less active than the original protoplasm, and 

 is unable to incorporate either amino acids or foreign protein molecules, 

 only being capable of assimilizing a certain protoplasm having a 

 weaker assimilase action. 



If the assimilase action of a virus is stronger than that of the 

 protoplasm of a cell to which the virus is adsorbed, the arrangement 

 of the polar groups of the protoplasm will be so changed as to become 

 identical with that of the virus. Since this change may be transmitted 

 throughout the protoplasm, the whole protoplasm protein may be 

 changed finally to have the identical arrangement. If the protoplasm 

 is disintegrated into coagulated elementary bodies by this change, the 

 bodies may be regarded as virus particles. This is the way in which 

 viruses multiply. 



The mode of change of the protoplasm of red blood cells can be 

 studied by investigating the mechanism of haemolysis. An incubation 

 period required for the commencement of haemolysis after addition of 

 a haemolytic agent can be regarded as the period during which a 

 change, secondarily induced by the haemolytic agent, spreads throughout 

 the protoplasm, /. e., the stroma of the red cell, to reduce the proto- 

 plasm incapable of retaining the haemoglobin which is being held by 

 the stroma. 



A similar incubation period is found commonly between the addi- 



