128 Kecognitwn of the Individual hy Haemolntic Methods 



of a normal ox and then tested on the corpuscles of 110 different 

 individual cattle. It was found that the mixture was powerfully 

 haemolytic for the corpuscles of every one of these 110 individuals 

 but absolutely without action ou the corpuscles of the individual 

 for which it had been exhausted. A number of other tests was made 

 by exhausting the serum with the corpuscles of various individuals 

 and similar results were always obtained, except in the case of close 

 blood-relations where certain exceptions occur which will be referred 

 to later. 



We may therefore conclude that the red blood corpuscles of any 

 individual (excluding for the moment the question of close blood- 

 relations) possess characters which differentiate them quite distinctly 

 from the red blood corpuscles of any other individual even of the same 

 species. 



Being now in possession of a method of identifying the corpuscles 

 of a certain individual even in the presence of corpuscles of other 

 individuals, it was possible to study the question of what happens when 

 the corpuscles of one individual are introduced into the circulation of 

 another individual of the same species. Eight oxen were injected 

 intravenously with the fresh blood of other oxen, quantities of from 

 two to four litres of blood being injected. In all these animals a 

 similar course of events was observed, the number of the foreign 

 corpuscles in the circulation gradually diminishing until they dis- 

 appeared after a lapse of from four to seven days after the injection. 

 Shortly after the disappearance of the foreign corpuscles from the 

 circulation, the blood .serum began to acijuire haemolytic properties. 

 These experiments emphasise in a most striking manner the definite 

 individuality of the red blood corpuscles, and we see that the injected 

 corpuscles are not merely not accepted by their new host, but are 

 regarded as definitely foreign and in f;ict give rise to the formation 

 of corresponding antibodies in accordance with the general laws of 

 immunity. 



Having found that it was po.ssible to distinguish the corpuscles 

 of non-related individuals of the same species several tests were made 

 on the corpuscles of closely related individuals. A mixture of a large 

 number of haemolytic sera was exhausted separately with the corpuscles 

 of a cow and her calf It was found that while exhaustion of the serum 

 with the corpuscles of the calf removed the haemolysin for the calf 

 only, exhaustion of the serum with the corpuscles of the cow removed 

 the haemolysin not only for the cow but also for the calf. A similar 



