132 SUPER-OKGANIC EVOLUTION 



by social organisation, let us examine some cases of 

 experimental medicine that are highly instructive. 



There exist some animals, like the hen, that are 

 insusceptible to carbuncle. It was thought that 

 this immunity was due to its higher temperature 

 compared with that of man. Pasteur carried out 

 a very simple experiment in order to show that the 

 amount of heat might influence this immunity. 

 He placed a hen with its claws constantly bathed 

 in cold water, until he obtained a lower tempera- 

 ture ; this once obtained, the carbuncle was 

 developed and the hen sickened. The experiment 

 appeared conclusive. Gibier, however, made with 

 the frog, an animal also indisposed to carbuncle, a 

 similar experiment. In order to raise the frog's 

 temperature, he placed it in a bath at a temperature 

 of 35 Cent., and under these conditions the animal 

 lost its immunity, and was susceptible to the car- 

 buncle bacillus. 



Canalis and Morpurgo have made hens and 

 pigeons lose their immunity, but in a different 

 manner, to which we especially call attention, 

 namely, by means of hunger. Submitting the 

 creatures, the subject of the experiment, to a 

 prolonged fast, the hens and pigeons also ended by 

 being victims of those terrible bacteria ; and, note 

 well, under normal conditions these creatures are 

 entirely immune. 



