DEPARTMENT OF EXPERIMENTAL EVOLUTION. 107 



the egg proteins, the ovalbumen, ovomucoid, ovoIobuHn, etc., as 

 containing not only all of the amino acids necessary for the formation 

 of such complex proteins as the hemoglobin, but also that each amino 

 acid is present in the egg in exactly the quantity which will be later 

 needed by the growing organism. 



His results show conclusively that synthetic action does take place, 

 that the simpler mon-amino acids are in some manner transformed 

 into the more complex constituents of the cell nucleus. Aside from 

 this synthetic action it was found that there was a selective utiliza- 

 tion of the nitrogen fractions which were "burned" to furnish the 

 energy of development (Entwicklungsarbeit) . Only 25 per cent of 

 the expected "amide nitrogen" was utilized, only 50 per cent of the 

 expected "arginine nitrogen," only 75 per cent of the expected 

 "lysine nitrogen," none of the "cystine" or "histidine nitrogen," 

 while the deficit caused by the non-utihzation of the basic nitrogen 

 was filled by the elimination of the mon-amino nitrogen far in excess 

 of the expected quantity (88.30 per cent, expected 57.65 per cent) . 



Pigment-forming Processes and their Control, by R. A. Gortner. 

 Dr. Gortner has continued his study of the melanins. He reports : 



In the study of the melanins considerable additional work has been done, 

 but only one paper has been completed. Inasmuch as it is practically a 

 certainty that the melanins are formed by the action of tyrosinase on some 

 chromogen, the nature of the chromogen involved becomes of paramount 

 importance. The melanin which I have isolated from black wool is of a 

 protein nature, and in this instance the chromogen must involve a protein 

 or a peptide. In order to test whether this chromogen is a part of the 

 normal keratin structure or whether it is a special body, elaborated solely 

 for the purpose of pigment formation and not utilized in the hair structure 

 when there is a lack of enzyme action (albinos) or when there is an inhibi- 

 tion of oxidase action (dominant whites), I have made a complete analysis 

 of the nitrogen ratios in both black wool and in white wool taken from the 

 same animal. The results of the analyses do not absolutely prove either 

 hypothesis, but they tend to support the belief that the chromogen is not 

 present in the unpigmented wool structure, but that it is introduced in 

 an oxidized form into the blapk wool solely as a foreign substance. 



Aside from this conclusion the work was of interest as being the first 

 analysis on record of pigmented and unpigmented hair structures taken 

 from the same animal, and also as furnishing confirmatory evidence for my 

 previous contention that hydrolysis with strong mineral acids breaks down 

 the melanin molecule. 



Relationship between Morphological Characters and Chemical Composition, 

 by J. A. Harris and R. A. Gortner. 



The analysis of the physiological causes of variation has been one 

 of the chief phases of Dr. Harris's work since coming to the Station. 

 Studies of fertility and of selective elimination have both furnished 

 the most convincing evidence of the association of physiological with 

 morphological variations. Of course, the suggestion follows at once 



