68 Chemical Basis of Genus and Species 



sera agglutinate the blood corpuscles of individuals of 

 the other groups, but not those of individuals belong- 

 ing to the same group. The phenomenon that a serum 

 agglutinates no corpuscles (Group i), or that the cor- 

 puscles are agglutinated by no serum (Group 4), are 

 the exceptions. It is obvious that, as far as our problem 

 is concerned, only Groups 2 and 3 are to be considered. 

 There is no Mendelian character which refers only to 

 one half of the individuals except sex. Since nothing 

 is said about a relation of Groups 2 and 3 to sex such 

 a relation probably does not exist. 



8. The facts thus far reported imply the suggestion 

 that the heredity of the genus is determined by proteins 

 of a definite constitution differing from the proteins of 

 other genera. This constitution of the proteins would 

 therefore be responsible for the genus heredity. The 

 different species of a genus have all the same genus 

 proteins, but the proteins of each species of the same 

 genus are apparently different again in chemical con- 

 stitution and hence may give rise to the specific bio- 

 logical or immunity reactions. 



We may consider it as established by the work of 

 McClung, Sutton, E. B. Wilson, Miss Stevens, Morgan, 

 and many others, that the chromosomes are the carriers 

 of the Mendelian characters. These chromosomes 

 occur in the nucleus of the egg and in the head of the 

 sperm. Now the latter consists, in certain fish, of 

 lipoids and a combination of nucleinic acid and pro- 



