MICRO-ORGANISMS IN RELATION TO MAN. Io! 
the artificial cultures ; but under no circumstances could it be 
communicated to birds. Pasteur, by a most ingenious experi- 
ment showed the reason of this immunity; and if any more 
evidence were needed, the results of this experiment proved, 
without doubt, the causal relationship of the micro-organisms 
to the disease. It was proved by a series of experiments that 
the development of the organisms of splenic fever is checked 
by a temperature of 111° F., and may it not be, said Pasteur, 
that birds are protected from the disease because their blood 
is too warm—not far removed from the temperature at which 
the splenic fever organisms will no longer grow? Might not 
the vital resistance encountered in the living bird suffice to 
bridge over the small gap between 107° and 111° F. A certain 
resistance in all living creatures to disease and death must be 
allowed; and there can also be no doubt the body of an 
animal would not be so favourable to the development of a 
micro-organism as would a suitable nutritive liquid contained 
in a glass vessel. If, too, the organism is aérobic, that is, if it 
requires a supply of oxygen for its life and growth, as does the 
anthrax bacillus, it can only develop in blood by withdrawing 
the oxygen from the blood-globules, which themselves retain 
it with a certain force for their own requirements. Nothing 
was more legitimate, said Pasteur, than to suppose that the 
corpuscles of the blood of the fowl had such an avidity for 
oxygen that the cells of the splenic bacillus were deprived of 
it, and that their multiplication was thus rendered impossible. 
These considerations led Pasteur to ask the question—‘‘If the 
blood of fowls were cooled, could not the splenic fever organ- 
ism live in this blood ?” 
The experiment was made. A hen was taken, and after 
inoculating it with splenic fever blood, it was placed with its 
feet in water at 77° F. The temperature of the blood of the 
hen went down to 98° or 100° F. —_—At the end of 24 hours the 
fowl was dead, and its blood was filled with the cells of the 
bacillus. 
