Place of Definition) etc., m Philosophical Biology 



species drawn from investigations on the blood of higher 

 animals, recall the results of Reichert and Brown on 

 the crystallization of hemoglobin. Here is one of their 

 statements : 



"Each form, #-oxyhemoglobin, &-oxyhemoglobin, 

 etc., appears always in its own proper form and axial 

 ratio when the blood of different individuals of the 

 same species is examined. . . . But upon comparing 

 the corresponding substances in different species of a 

 genus, it is generally found that they differ one from 

 the other to a greater or less degree; the differences 

 being such that when complete crystallographic data 

 are at hand the species can be distinguished by these 

 differences in their hemoglobins." 



Let us assume there is ground for questioning the 

 full trustworthiness of this conclusion. Notice the 

 strong presumption of its general reliability produced 

 by its accordance with evidence from a wholly different 

 kind of research on the serum of blood, namely, that on 

 the precipitin reaction; and from still another kind, 

 namely, that on the hemolytic action of one blood upon 

 another. Nor should we fail to recognize the converg- 

 ence of evidence for chemical specificity of organisms 

 drawn from comparative investigation on milk, on the 

 enzymes of digestion, and from such direct analyses of 

 organic structure as those of the sperm of many spe- 

 cies and genera of fishes. I mention only one other line 



