102 The Unitt/ of the Organism. 



contains nearly the same number of equivalents of the 

 precipitate. 



In liis well known work Blood Immunity and Blood Re- 

 lationship, G. Nuttall has applied this principle more widely 

 to the animal kingdom than any one else. 



(t) Comparative Chemistry of the Sperm of Different 



Species of Fishes 



Several biologists are impressed with the importance of 

 knowledge in tliis field as bearing on philosophical natural 

 history. No physiologist has so far as I am aware, ventured 

 fjuite so far into the realm of prophecy with reference to it 

 as has E. Abderhalden. He points out the possibility of 

 increasing the number of attributes now recognized as dis- 

 tinguishing not only species but individuals through a sys- 

 tematic and concerted carrying out of researches already 

 begun in this field, and foresees the time when biochemistry 

 will play a leading role in problems of racial descent and 

 taxonomic affinity.^^ The march of research in the decade 

 since Abderhalden made these forecasts, has undoubtedly 

 been toward a fulfillment of them, at least as touching bio- 

 chemical distinctions between individuals. Thus C. Todd 

 has very recently given a useful summary" of what has been 

 done up to the present hour on the comparative chemistry 

 of the blood as revealed by the methods here being consid- 

 ered, and an account of an exceedingly interesting resarch 

 of his own. 



The chemico-zoological researches standing next in in- 

 terest and importance to those on the blood are the well 

 known ones inaugurated by Miescher and continued by Kos- 

 sel and liis students, on the spermatozoa of fish. ]\Iiescher 

 discovered in the spenii of the salmon a group of protein 

 substances called by him protamines, which are said not 

 to have been found as yet elsewhere than in fish sperm. 



