12 Transactions of the Society. 



diffused over the cell, not more than half-a-dozen little particles 

 that could he distinguished as having possibly been monads, could 

 be seen. And it continued thus, in the first experiment, for a little 

 over five hours. At the end of this time there was a quick passage 

 across the edge of the field, which, on being further searched for, 

 and followed, was seen to be one of the monads in question, only it 

 had attained to but half its development. Fig. ] 3 (Plate II.) is a 

 drawing of it magnified to the same extent as the one in Fig. 11, 

 and placed for comparison at 13a, magnified to the same extent as 



13 ; and this was followed for two hours, when it had attained the 

 full size and entered upon fission. Meantime the cell had be- 

 come inhabited by many other partially and fully developed forms 

 of the same organism. 



This was repeated, and with very similar results. 



It is thus plain that a temperature of 212° was not destructive 

 of this germ. 



For the employment of higher temperatures a digester was, of 

 course, needful. For this purpose simple tubes terminating in a 

 cell, such as are seen in Fig. 1, were used ; the bulb or reservoir 

 and appendage for air being dispensed with. "So that, in fact, 

 in this condition we have nothing but the tube with a slight 

 enlargement at one point, terminating in a funnel, for receiving 

 the spores and septic fluid at one end, and in a delicate cell for 

 microscopic work at the other. 



As before, the spores were found and at once placed in the tube, 

 ^the cell of which had been previously filled to prevent delay when 

 the spores on the broken glass were ready to be put in. 



When experiments were made upon the spores of the six 

 monads in a dry heat, It was found that the utmost temperatures 

 the spores could resist, without devitalization, ranged, in the various 

 forms, from 250^ Fahr. to 300° Fahr. The one we are now con- 

 sidering could, by means of its spores, just survive a temperature of 

 300"^ Fahr. This was repeatedly witnessed by myself and colleague, 

 and has been confirmed by two carefully arranged subsequent tests, 

 conducted on the same principle. After enduring this temperature 

 for from five to ten minutes, the spores properly remoistened 

 developed, in some instances, as before. Beyond this temperature 

 they were destroyed. 



I determined, therefore, to begin with this in the case of heat 

 endured in fluid. 



In one of the tubes the actual spore was inserted, and the tube 

 hermetically sealed. As control experiments, five other tubes were 

 fiUed with the fluid containing the organism, but in which there 

 was no a priori certainty that the spore would be. These were 

 also hermetically sealed. 



The whole six tubes were placed in a small digester and heated 



