DIFFERENTIALS AND EVOLUTION 591 



protamines or histone-like substances with nucleic acid, and that the prota- 

 mines and histones of the sperm differ in different species of fishes as regards 

 the nature and grouping of their amino-acids. But there is apparently no direct 

 parallelism between the chemical relationship of these substances in different 

 species and the phylogenetic relationship of the latter, and two different species 

 of Salmonidae may contain identical protamines. Furthermore, according to 

 A. E. Taylor, Gay and Robertson, and Wells, it is not possible to produce 

 species-specific immune bodies against protamines and histones. But, these 

 simple proteins develop perhaps from more complex nuclear proteins which 

 may be present in the cells from which the spermatozoa are derived, or else these 

 may be admixed to the suspension of spermatozoic substances which are anti- 

 genic and bear organismal differentials. Accordingly, through injection of fish 

 sperm into rabbits, Kodama could obtain specific immune sera, which reacted 

 with the spermatozoa of their own as well as of related species, but not with 

 the extract of fish muscle, and which were therefore organ- or tissue-specific ; 

 yet these immune sera possessed also organismal differentials as shown by 

 the fact that they reacted in a graded way with the spermatozoa of different 

 species of fishes, in accordance with the phylogenetic relationship of these 

 species. We must then assume that substances other than protamines act 

 as antigens in this case. In the sperm of mammals we find instead of the simple 

 protamines or histone-nucleic acid combinations in fishes, more complex 

 nucleo-proteins. These substances may serve as antigens, which call forth 

 immune reactions against the organ as well as against the organismal differ- 

 entials or their precursors contained in the sperm. Also, other animal proteins 

 may have a species-specific character. 



Other instances are known in which differences in species are associated 

 with differences in the structure of proteins, although these data do not con- 

 tribute to an understanding of the evolutionary changes which have taken 

 place in the proteins. Thus, the constitution of globin in the hemoglobin 

 molecule differs in different species in regard to the relative amounts of amino- 

 acid nitrogen present and the proportion between lysin and histidin, on the 

 one hand, and arginin, on the other hand. Osborne and Gortner observed a 

 certain parallelism between the chemical relationship of the seed proteins in the 

 wheat and barley groups and the phylogenetic relationship of the species in 

 which they occurred, and these differences in chemical relationship cor- 

 respond to immunological reactions (Wells). 



As to the chemical constitution of individuality differentials, it is almost 

 certain that here, too, proteins are involved. The individuality differentials 

 cannot as a rule be detected by chemical or immunological analysis of blood 

 sera, but under certain conditions they have been detected in erythrocytes by 

 means of immunological methods. The great difficulty in the chemical analysis 

 of the individuality differentials lies in the fact that the preparation of proteins 

 of cells and tissues for study in many cases causes their denaturation and this 

 change injures the individuality differentials, which evidently possess very 

 delicate chemical characteristics. 



Not only does the phylogenetic evolution tend in the direction from coarser 



