498 The University Science Bulletin. 



its transformation is under the control of the environment. Protein 

 synthesis is in no way to be confused with the energy-producing re- 

 action. In the body, anything which increases metabolism will lead 

 to growth. Increase this still more and protein destruction results. 

 This accounts for the appearance of split products of protein in 

 muscle which has suffered excessive stimulation (see Bayliss for lit- 

 erature) and the destruction of the tissue by strong growth stimuli 

 such as X-ray, radium, coal tar, arsenic, etc. 



Such a machine can build itself in the manner that it does because 

 it utilizes the products of its energy-producing reaction for its build- 

 ing. The building is only the sequence of change its original funda- 

 mental structure undergoes to produce the final necessary work — 

 the work of supplying an adequate amount of fuel for a certain pe- 

 riod of life and supplying the egg with an adequate supply of this 

 material (yolk) to carry it through the early period of the develop- 

 ment of the whole. This yolk supply decreases progressively. This 

 decrease leads to the changing character of the syntheses. 



The extracellular deposits which I have described above as im- 

 portant for the organization peculiar to the dynamic state of later 

 life are evidently the substratum recognized by Child. They are the 

 result of protein syntheses peculiar to the organization of a certain 

 period of the development of the whole. They must be the result 

 not only of mechanical but also chemical changes in the environ- 

 ment. The picture of the organization as it is seen through the study 

 of the cells is in no sense the picture of one continuous metabolic 

 change. It is the primary building of a heterogenous system fol- 

 lowed by the gradual decline of this system to a state of static 

 equilibrium. Elemental life and elemental death are not compar- 

 able to systemic life and systemic death. The body is the necessary 

 cycle that these cells may preserve their kind. For the active growth 

 of the early period of the development the cell draws upon the yolk 

 or the mother for its supply of those substances necessary for this 

 growth. The disappearance for this supply of material is the ap- 

 pearance of the second, or the functioning, period. The building of 

 this period is completed within ten days after birth in man, except 

 for the laying down of the nerve sheath. The syntheses peculiar for 

 this building are the result of the disappearance of the substances 

 carried in the yolk. The important factors for differentiation are 

 not to be found, therefore, in the primary reactions of the cells, but 

 in the deficiencies of these cells. The important deficiency which 



