SPECIAL PROPERTIES OF BLOOD SERUM. 269 



referred to already. A foreign blood introduced into the cir- 

 culation of an animal of a different species brings about a 

 variety of changes; clots are sometimes formed and from re- 

 sultant changes in pressure serous exudations may follow. 

 Hemoglobinuria is a general consequence and this of course 

 results from a breaking down of blood corpuscles in quantity. 

 It has been assumed by some writers that this hemolytic 

 effect is possibly clue to altered osmotic pressure in the blood, 

 as similar phenomena are brought about by the admixture of 

 blood with weak solutions. But the peculiar specificity of 

 artificial hemolysis shows that this explanation is not satis- 

 factory. 



If the blood of man, for example, receives an injection of 

 human blood under proper condition no harm results, but if 

 ox blood be used the case is different. A large transfusion of 

 the ox blood might be at once fatal, the hemolysins of that 

 destroying the human corpuscles. On the other hand trans- 

 fusion of small amounts of ox blood would have different 

 effects varying with the manner of transfusion. \Yith but 

 little ox blood added the human hemolysins would be greatly 

 in excess and by their chemical mass action would bring about 

 a relatively great destruction of the ox blood corpuscles, while 

 the corpuscles of the human blood would suffer but little 

 change. But more than this would probably take place as 

 illustrated by w r hat has been observed with certain lower ani- 

 mals. The serum of the eel is especially destructive of the 

 corpuscles of rabbit's blood and a large injection of eel serum 

 into the rabbit would produce death. With repeated small 

 doses, however, the rabbit's blood is stimulated to develop the 

 antitoxin or antihemolysin which protects against the eel 

 serum poison. A condition of immunity is thus reached, and 

 what has been shown for the rabbit has been shown for other 

 animals. An explanation of the origin of the hemolysins will 

 be offered below, but now we are concerned only with the 

 fact. 



In the above cited experiment the eel serum develops gradu- 



