ORIGIN OF LOWEST ORGANISMS. 



ditions, we have the best proof that can be obtained 

 of their death. 



Having made many experiments with solutions of 

 ammonic tartrate and sodic phosphate, I have almost 

 invariably observed that such solutions when exposed 

 to the air without having been boiled become turbid 

 in the course of a few days owing to the presence of 

 myriads of Bacteria and Vibriones, with some Torulce. 

 These organisms seem to appear and multiply in such 

 a solution almost as readily as they do in an organic 

 infusion. On the other hand, having frequently boiled 

 such solutions, and closed the flasks during ebullition, 

 I have invariably found, on subsequent examination 

 of these fluids, that whatever else may have been met 

 with, Bacteria and Vibriones were always absent. The 

 difference was most notable, and it seemed only intel- 

 ligible on the supposition that any living Bacteria or 

 dead ferments which may have pre-existed in the 

 solution, were deprived of their virtues by the pre- 

 liminary boiling. These experiments also seemed to 

 show that such solutions, after having been boiled, and 

 shut up in hermetically-sealed flasks, from which all 

 air had been expelled, were quite incapable of giving 

 birth to Bacteria. The unboiled fluid, exposed to the 

 air, might have become turbid, because it was able to 

 nourish any living Bacteria which it may have con- 

 tained, or because it was capable of evolving these de 

 noyo, under the influence of dead ferments whose ac- 

 tivity had not been destroyed by heat. Hence we have 



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