TISSUE-CULTURE IN VITRO II5 



had led him to admit that with age blood-serum accumulates 

 toxines which are increasingly noxious or abundant. He had 

 convinced himself of this fact by a series of experiments. 

 One of these is particularly striking and deserves to be men- 

 tioned, especially as it was never published. 



There was at the Rockefeller Institute, before the war, a 

 dog nearly eighteen years old. This poor animal never stirred 

 from its corner and could hardly get up to eat. He slept all 

 day, his coat was coming out, his eyes were dim, and his 

 eyelids stuck together. 



This animal was anaesthetized, put on the operating table 

 and treated as follows. Carrel bled him by the carotid 

 artery and removed nearly two-thirds of his blood. This 

 blood was collected aseptically and immediately centrifuged, 

 so as to separate the red cells from the serum. The red cells 

 were washed in Ringer solution, recentrifuged and mixed 

 with fresh Ringer solution to re-establish the initial volume of 

 the blood. This was then re-injected to the dog. The cir- 

 culation was restored by massaging the heart, and the skin 

 was sewn up. A prince of royal blood, heir to the throne, on 

 whom the peace of the world depended, could not have been 

 the object of more attentive care than this old animal. After 

 several days he had regained strength and appetite. The 

 same operation was repeated so as to eliminate practically all 

 the serum of his blood and replace it by this artificial solution 

 which, besides the blood cells, contained only salts such as 

 chlorides of sodium, potassium, and calcium in the same 

 proportion as those found in the blood. The animal lived. 

 Not only did he live, but, once over the operative shock, he 

 was a different dog. He ran and barked, a thing he had not 

 done for years. His eyes were clear, his eyelids normal. His 

 coat started to come in; he was gay, active, and most important 

 of all, he was no longer indifferent to the charms of the other 

 sex. He was regenerated. 



The logical conclusion which Carrel deduced from this re- 

 markable experiment was that his hypothesis on the increase of 

 toxicity of serum with age was verified, and that the symptoms 



