PUTREFACTION AND INFECTION. 65 



Infusoria, which appeared to have driven the Bacteria 

 from their habitat, as few of the latter were to be seen. 

 My inability to find the larger creatures a second time 

 in such numbers perplexed me, causing me to conclude 

 that I had accidentally alighted upon a colony of them- 

 My experience with the unclean pipettes already de- 

 scribed, pointed, however, to another source. 



While three days sufficed to break down their purity, 

 and to fill the six exposed tubes with Bacterial life, the 

 six protected ones remained for more than three months 

 as clear and healthy as they were on the day the infu- 

 sion was poured into them. Neither a trace of mould 

 upon the surface^ of any one of them, nor a trace of tur- 

 bidity in its mass, was to be seen. 



Into another chamber containing three test-tubes a 

 very strong infusion of hay was introduced on the 1st of 

 October. It was boiled for five minutes, and then aban- 

 doned to the air of the case. Three other tubes exposed 

 to the laboratory air were placed on a stand beside the 

 case. The colour of the infusion was very deep, but it 

 was quite transparent. One of the outer tubes was 

 diluted with distilled water. On the 3rd the infusion 

 in this tube was turbid, the other exposed ones remain- 

 ing clear. The unseen germinal matter had in some 

 way or other invaded the distilled water, and made it 

 infective. The dilute infusion contained multitudes of 

 Bacteria, many motionless, but many moving rapidly 

 about. On the 4th of October all the tubes swarmed 

 with Bacteria. They continued muddy till the middle 

 of November, when they were employed for experi- 

 ments on infection. 



Throughout the whole of this time the ^protected 

 tubes remavned uncha/nged. 



With regard to infection, it may be stated here that 



