MIRACLES OF SCIENCE 



oculated with the blood serum of a cat, will develop 

 an anti-feline serum; and so for all other tribes of 

 animals, including not merely mammals but birds, 

 reptiles, and even crustaceans, such as the lobster 

 and its allies. 



The explanation of the development in the body 

 of the rabbit of the peculiar quality of blood that 

 gives the anti-serum its value in such tests as those 

 outlined, is found in the fact that the blood of almost 

 any animal has a certain quality of toxicity when in- 

 jected into the veins of an animal of different species. 

 In some cases this action may be very virulent. 



For example, fifteen drops of the blood of an eel 

 injected into the veins of a dog weighing about 

 thirty pounds may produce death in seven or eight 

 minutes. 



In another experiment ten drops of the blood 

 serum of an eel killed a rabbit of ordinary size in 

 two-and-a-half minutes. The foreign blood serum 

 appears to attack the blood corpuscles, rendering 

 them functionless and presently dissolving them. 



Curiously enough the blood corpuscles of new- 

 born rabbits are much more resistant to foreign 

 blood than are those of the adult rabbit. But a cer- 

 tain degree of resistance obtains in all animals, and 

 this may be accentuated by introducing a very small 

 quantity of foreign blood serum, and from time to 

 time repeating and increasing the dose. In this way 

 the system of the animal becomes to some extent 

 immune to the poisonous effect of the foreign blood, 

 through development of what for want of a better 

 term is called an anti-serum. 



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