18731877 255 



that, no organisms were produced, as was stated in the thesis 

 of M. Chamberland, then a curator at the laboratory, and who 

 took an active part in these experiments. 



A chapter might well have been written by a moralist " On 

 the use of certain opponents " ; for it was through that discus- 

 sion with Bastian that it was discovered how it was that at 

 the time of the celebrated discussions on spontaneous genera- 

 tion the heterogenists , Pouchet, Joly, and Musset, operating 

 as Pasteur did, but in a different medium, obtained results ap- 

 parently contradictory to Pasteur's. If their flasks, filled with 

 a decoction of hay, almost constantly showed germs, whilst Pas- 

 teur's, full of yeast water, were always sterile, it was because 

 the hay water contained spores of the bacillus subtilis. The 

 spores remained inactive as long as the liquid was preserved 

 from the contact of air, but as soon as oxygen re-entered the 

 flask they were able to develop. 



The custom of raising liquids to a temperature of 120 C. 

 in order to sterilize them dates from that conflict with Bastian. 

 " But," writes M. Duclaux, "the heating to 120 of a flask 

 half filled with liquid can sterilize the liquid part only, 

 allowing life to persist in those regions which are not in contact 

 with the liquid. In order to destroy everything, the dry walls 

 must be heated to 180 C." 



A former pupil of the Ecole Normale, who had been a curator 

 in Pasteur's laboratory since October, 1876, Boutroux by name, 

 who witnessed all these researches, wrote in his thesis : " The 

 knowledge of these facts makes it possible to obtain absolutely 

 pure neutral culture mediums, and, in consequence, to study 

 as many generations as are required of one unmixed micro- 

 organism, whenever pure seed has been procured." 



Pasteur has defined what he meant by putting tubes, cotton, 

 vases, etc. , through a flame. " In order to get rid of the micro- 

 scopic germs which the dusts of air and of the water used for 

 the washing of vessels deposit on every object, the best means 

 is to place the vessels (their openings closed with pads of cotton 

 wool) during half an hour in a gas stove, heating the air in 

 which the articles stand to a temperature of about 150 C. to 

 200 C. The vessels, tubes, etc., are then ready for use. The 

 cotton wool is enclosed in tubes or in blotting-paper." 



What Pasteur had recommended to surgeons, when he ad- 

 vised them to pass through a flame all the instruments they 

 used, had become a current practice in the laboratory ; the least 



