96 THE NATURE AND ORIGIN OF LIFE 



us, in particular, to distinguish cow's milk from all other 

 milks. The specific serum thus obtained gives a precipitate 

 neither with asses' nor woman's nor sow's milk. 



In like manner inject into the peritoneum of a guinea- 

 pig red blood globules from a goose. We find that these 

 globules are little by little digested and assimilated by the 

 guinea-pig, and that henceforward the guinea-pig's serum 

 has the property of dissolving in vitro the blood globules of 

 the goose. 



This result has been generalized for a great number of 

 tissues. Each of them, when assimilated by a given animal, 

 develops in the animal's blood a transportable quality which 

 is specific in relation to the tissue assimilated. 



We can understand all the practical importance of such 

 a discovery ; it contains all serumtherapy in itself. If you 

 habituate a horse to assimilating diphtheritic toxin, its 

 serum will be capable of destroying the toxin in a child 

 attacked by the terrible malady, provided the serum of 

 the horse is so prepared as not to be itself a poison to the 

 child. This is the general method discovered by Behring 

 and Kitasato, and made applicable by the efforts of Emile 

 Roux. 



To tell the truth, we already knew of an analogous trans- 

 portability of functional properties by dead colloids. A 

 filtered culture of anthrax bacteridia, if a sheep were inocu- 

 lated with a sufficient quantity of it, might bring on fatal 

 disease with symptoms analogous to those of bacteridian 

 anthrax. But at the beginning this result of observation 

 was not interpreted as it is now. It was thought that, in 

 the disease caused by anthrax, the excrementitial substances 

 produced by the bacteridia played the principal part an 

 opinion that will also have to be discussed later. 



In fact, when we filter a culture bouillon of anthrax 



