OKIGINATION OF LIVING BEINGS. 75 



tion, because it induced a distinguished French chemist, 

 M. Pasteur, to take up the question on the other side ; 

 and he lias certainly worked it out in the most perfect 

 manner. I am glad to Bay, too, that he lias published 

 his researches in time to enable me to give vou an ac- 

 count of them. lie verified all the experiments which 

 1 have just mentioned to you — and then finding those 

 extraordinary anomalies, as in the case of the mercury 

 bath and the milk, he set himself to work to discover 

 their nature. In the case of milk lie found it to be a 

 question of temperature. Milk in a fresh state is 

 slightly alkaline; and it is a very curious circumstance, 

 but this very slight degree of alkalinity seems to have 

 the effect of preserving the organisms which fall into 

 it from the air from being destroyed at a temperature 

 of 212°, which is the boiling point But if you raise 

 the temperature 10° when you boil it, the milk behaves 

 like everything else; and if the air with which it conies 

 in contact, after being boiled at this temperature, is 

 passed through a red-hot tube, you will not get a trace 

 of organisms. 



He then turned his attention to the mercury bath, 

 and found on examination that the surface of the mer- 

 cury was almost always covered with a very fine dust. 

 He found that even the mercury itself was positively 

 full of organic matters; that from being constantly 

 exposed to the air, it had collected an immense num- 

 ber of these infusorial organisms from the air. Well, 

 under these circumstances he felt that the case was 

 quite clear, and that the mercury was not what it had 

 appeared to M. Schwann to be — a bar to the admission 

 of these organisms ; but that, in reality, it acted as a 

 reservoir from which the infusion was immediately 



