372 V. THE NATURE OF EVOLUTION 



coagulation and the rapidly occurring activation of a variety of enzyme 

 systems after the fertilization of egg may be ascribed to the activa- 

 tion of latent enzymes by the liberation of active group. In these 

 cases the unfolding of the active group must be caused also by proper 

 stimuli. 



The long lasting immunity against viruses is based upon the per- 

 sistence of the virus patterns in the host but in animals only the 

 back-bone structure is remaining, so that virus detection in the host is 

 hardly possible. In contrast to animals, however, the virus is detected 

 without difficulty in plants having become resistant to the virus after 

 the infection, showing that there is a considerable difference between 

 animals and plants in their protoplasm protein, that is, plant proto- 

 plasm protein may exist usually in an unfolded state, or a slightly 

 folded state to be readily unfolded unlike that of animals. 



In this respect bacteria are similar to higher animals, a fact which 

 may depend upon the parasitic nature of the bacteria on higher animals 

 from which they are inherited the protein. If so, the bacteria pai'a- 

 sitic on plants may have the protein similar to that of the plants, 

 although the writer cannot find any report corroborating this suppo- 

 sition. The view that plants are thus different from animals in the 

 character of protoplasm protein is also supported by the already men- 

 tioned fact that plant protein can fuse readily into protoplasm-like 

 masses and that plant viruses are inclined to be obtained in crystal 

 shapes, indicating the strong tendency of the protein to combine 

 mutually. This is probably due to the presence of free polar forces 

 mutually attracting. Further, there is another evidence corroborating 

 this view. Namely the reduction to young primitive structure is 

 readily raised in plant tissues, that is, cancer-like proliferative cells 

 and germ cell-like regenerative ones and even germinal cells them- 

 selves seem to be produced in every tissue of plants, thus their re- 

 generative faculty being striking and no peculiar cells being needed 

 for the production of germinal cells, whereas in animals specific cells 

 are necessary for the germ-cell production and the regenerative faculty 

 is insignificant. 



In order that the differentiated pattern is reduced to the primitive- 

 ness the unfolding of the protein structure is indispensable. Therefore, 

 it may naturally follow that the return to the primitive structure 

 takes place only with difficulty in animals in which the unfolding of 

 the protein hardly occurs. 



In the preceding chapter the writer assumed the presence of the 

 mechanism in animals which can prevent the return to the primitive 

 structure ; the character of difficult-unfolding must he regarded as 

 being this mechanism. The predisposition to cancers, therefore, must 



