The Organism and its Chemistry 99 



are alike, or even that only a few sorts can be demonstrated, 

 but that the great number of kinds do not correspond in 

 any definite way to different kinds of animals. And here 

 comes the particular point made against these views by 

 Heichert and Brown — and it is of great importance gener- 

 ally, and peculiarly interesting to the natural historian. 

 They show that the reason wlu' so many previous observers 

 have failed to find a correspondence between kinds of crys- 

 tals and kinds of animals, is that the crystals have not been 

 described zmth sufficie7it fulness and accuracy. In a word 

 the issue is, to the naturalist, the old and familiar one of 

 descrijjtion, comparison and classification. For example, 

 the authors lay particular stress upon the insufficient atten- 

 tion hitherto given to the crystal fomis of the different 

 sub-species of hemoglobins, namely, oxyhemoglobin, re- 

 duced hemoglobin, metoxyhemoglobin, methemoglobin, etc. 

 Again they point out the great inadequacy of earlier studies 

 in the determinations of the axial relations and other phys- 

 ical attributes of the crystals. The upshot of their cnti- 

 cism of previous studies as seen in the light of their own, 

 is that when a classification of hemoglobin crystals from 

 the blood of many kinds of animals is based on sufficiently 

 thorough going description, that classification correlates 

 itself with the kinds of animals from which the blood is 

 taken. 



(6) The Precipitin Reaction Between Bloods of Different 



Animals 



If our comparative chemical knowledge of vertebrate 

 blood were limited to the results of studies like this by 

 Reichert and Brown, the presumption in the absence of very 

 positive evidence to the contrary, would yet be strongly 

 in favor of the hypothesis that the blood of each animal 

 species is in some of its constituents unique to that species. 



