354 V. THE NATURE OF EVOLUTION 



protein, are determined in their structure by the protoplasm from 

 which they were produced, they will vary in their structures if the 

 cells from which they are to be produced are being changed as the 

 embryo is developed. It has been found that the press juices of chick 

 embryos of different incubation times acted differently on the growth 

 of cultures of fibroblastic cell (26), indicating that the composition of 

 the press juices which may act as hormones undergo changes during 

 development of the embryos, and so it can be concluded that the com- 

 position of the body fluid which can exert hormone-like effect is gradu 

 ally changing during ontogeny. 



In a study on growth and mortality effects produced in early 

 chick embryos by antiserum, results were obtained which point to the 

 possibility that there are different protein complexes which make their 

 appearance in the chick embryo concurrent with the embryo's develop- 

 ment (26a). Crystals of the haemoglobins of the human adult and of 

 the human foetus have different shapes (27) ; the difference is also de- 

 monstrable in their X-ray interferences (28), showing likewise that the 

 protein structure is changing during the course of development. The 

 change in protoplasm structure, which may vary with different re- 

 gions of the body, will thus be advanced with the formation of vari- 

 ous shapes and functions. 



In higher organisms, hormones are, of course, distinct from virus- 

 like agents, but at an early developmental stage of embryos or at an 

 extremely primitive stage of organisms, the difference between the 

 two might be subtle. If the protein, the main component of the proto- 

 plasm, is freed from the protoplasm in an orderly polymerized state, 

 it may function as a virus, but when the protein or other components 

 such as steroid having the pattern of the protoplasm are liberated 

 from the protoplasm, not forming orderly polymerized masses and 

 accordingly in a state unable to act as a virus, they may be able to 

 act as hormones and are capable of exerting their specific structural 

 influences, although unable to produce the exact replicas as do vi- 

 ruses. Consequently, primitive hormones may be regarded as incom- 

 plete viruses, only being capable of exerting on other protoplasm un- 

 certain influences specific to their structures. At such a primitive 

 stage, there might entirely be no essential differences between hor- 

 mones and enzymes (see Part IV, Chapter V). The specialization of 

 these factors must be advanced as the organisms are evolved or thf 

 embryos are developed. 



The differentiation of the protoplasmic structure, which may var; 

 with different parts of the embryo, may not only lead to the produc- 

 tion of different hormones or enzymes as well as of different virus-lik*. 

 agents, but also may cause the different distribution of inorganic salts 



