1 6 THE NEW CELL DOCTRINE 



student of medicine, or of biology, has opportunity in his prac- 

 tical laboratory work to see for himself the formations of the 

 dividing nucleus, and I may therefore allow myself to omit 

 a detailed description of this phenomenon. But there is 

 something else I should like to say to you concerning the 

 nuclei. It is now established that the nucleus has an entirely 

 different chemical composition from the protoplasm. In 

 protoplasm and in nucleus we have to do cheifly with proteids, 

 for they are the chief components of both structures. The 

 proteids in the nucleus are, however, in certain respects 

 simpler than those in protoplasm. For this and other reasons, 

 it is believed that the nutritive material must first reach the 

 nucleus in order to be worked over in the nucleus and to be 

 later returned from the nucleus to the protoplasm. The 

 chemical relations between the nucleus and the protoplasm 

 are of the greatest significance. I must ask you to consider 

 that I am not a competent biological chemist. In recent 

 years chemical biology has made many beautiful and im- 

 portant discoveries. It is understood that we must seek the 

 explanation of most vital phenomena in the chemical altera- 

 tions which occur in the body. If we should ever get so far 

 as completely to understand life it will be only when chemists 

 are in a position to explain vital phenomena chemically. We 

 incline to the belief that the nucleus is absolutely necessary 

 to the functions of life. It is besides instructive to learn that 

 in certain lower organisms, in which we can distinguish no 

 definite nucleus, such as we usually observe, nevertheless 

 nuclear substance occurs scattered in the protoplasm. From 

 such observations we draw the conclusion that for the main- 

 tenance of life it is necessary to have not only the complicated 

 protoplasm, but also the presence of the differently compli- 

 cated nuclear substance. We cannot hope to reach a basis 



