SKETCH OF M. LOUIS PASTEUR. 827 



ent in the solution, and if the solutions were then carefully sealed up 

 free from air. Nor was it necessary to exclude the air, provided that 

 pure air, free from germs, were admitted. By passing the air through 

 red-hot tubes or through gun-cotton before reaching the solutions, he 

 found that the development of organisms, in such boiled solutions, did 

 not take place. [A single exception was noticed in the case of milk, 

 which required a higher temperature to destroy the organisms.] 



Professor Pasteur also examined the gun-cotton through which the 

 air had been passed, and he found, among other things, certain cells 

 to which he attributed the power of causing the growth of organisms 

 in solutions. By sowing some of these cells in solutions which had 

 previously remained clear, and finding that such solutions speedily be- 

 came turbid from the growth of living organisms, it was proved that 

 the air which had passed through the gun-cotton had lost its property 

 of causing the development of life in solutions, because the germs 

 which the air contained had been stopped by the gun-cotton." The 

 results on this point might be summed up : " 1. No organisms are de- 

 veloped in solutions if care be taken to prevent the possibility of the 

 presence of germs ; 2. This negative result does not depend upon the 

 exclusion of oxygen ; 3. The matter separated from ordinary air is 

 competent to develop organisms in solutions which previously had re- 

 mained unchanged. Not less important were the results of Pasteur's 

 experiments respecting the chemical functions of the ferment. . . . 

 He proved that those conditions which are most favorable to the 

 healthy growth and development of the yeast-cell are most conducive 

 to the progress of fermentation, and that fermentation is impeded or 

 arrested by those influences which check the growth or destroy the 

 vitality of the cell. ... To the biologist, two of Pasteur's researches 

 are of very great importance. He has shown that fungi find all the 

 materials needed for their nutrition and growth in water containing an 

 ammonia salt and cei'tain mineral constituents, and devoid of any ni- 

 trogenized organic matter ; and he has proved that all the phenomena 

 presented by the destructive silk-worm epidemic, the pebrine (even 

 the singular fact that it is hereditarily transmitted through the female 

 and not through the male), are to be explained by the presence of a 

 parasitic organism in the diseased caterpillars." 



M. Pasteur's later researches have been continued in the same 

 direction as those which we have already mentioned, and have re- 

 sulted in a great expansion of the germ theory and its application to 

 useful purposes. Those which have so far been most fruitful in prac- 

 tical consequences are the investigations which he has made into the 

 cause of the cholera in fowls and of carbuncular diseases in cattle and 

 sheep, and into the means of preventing them by the cultivation of the 

 infectious germs in diluting fluids and inoculation with them inves- 

 tigations the results of which have already been heralded over the 

 whole earth, and the inestimable value and importance of which have 



