1878.] the Life-History of a Minute Septic Organism. 



347 



and heated up to the temperature of 240° F., 10° F. below the death- 

 point in the dry condition. It was kept at this for five minutes. 



As soon as it could be conveniently taken from the digester it was 

 placed in a " cradle " on the stage of the microscope. Nothing but 

 violent Brownian movement was visible anywhere ; and nothing more 

 than this could be seen by the end of twelve hoars, although the search 

 was very strict and systematic. For the next twen by-four hours no 

 other result ensued, and at the end of six days there was no trace of 

 the organism. The question now arose as to whether any incapacity 

 to sustain the organism had been superinduced. For this purpose the 

 tube was opened at its sealed end, and a small piece of platinum wire 

 which had been immersed in the fluid containing the living organism 

 was dropped into it. It was then sealed again and examined. In 

 the course of twenty minutes seven of the introduced organisms were 

 seen, and in the next two days they were present in great abundance. 



It thus became manifest that the previous sterility of the fluid in 

 the cell was due to the destruction of the germs, or spores, by the heat 

 to which the infusion had been subject. 



Another tube was now taken, and after preparation in all respects 

 in the same way, was heated in the digester to 230° F., and kept at 

 that for five minutes. 



The result was precisely the same as in the preceding instance. 

 There was no trace of the living organism from the first, on to the 

 end of a week. But in this case also, inoculation reintroduced it 

 successfully, and it flourished. 



I now determined that 220° F, should be tried; and after the tube 

 and its contents had been arranged as before, it was heated to that 

 point, and kept in that condition for five minutes. 



When first examined with a suitable lens, as before, nothing but the 

 well-known Brownian movement was visible. And this remained true 

 for the first five hours, although the whole cell was carefully examined 

 with the new formula T Vth and -^th inch objective, and repeatedly 

 "searched " with the Jth. But during the sixth hour I became con- 

 vinced that the organism in a developing condition was present ; it 

 was in a part of the cell immediately under the tube ; and in the course 

 of a few minutes I was perfectly satisfied that the organism in the 

 condition represented at fig. 22 was there, but only five could be seen ; 

 these, however, increased in size as usual, and in the course of forty 

 minutes three of them began gracefully to move, and following one of 

 them I saw it attain to the usual adult condition. The next day the 

 cell had scores of the organisms swimming in it. 



This experiment was now repeated, every detail of preparation being 

 as before. The results were similar ; that is to say, the living organism 

 reappeared ; but it was not found until the seventh hour, and then it 

 was freely swimming and in an almost perfect condition. But I could 



VOL. xxvii. 2 A 



