Boyal Microscoincal Society. 101 



chamber. After regular watching for ten hours we were enabled 

 to decide that the young forms of III. were found on four sHdes ; 

 the young forms of I. on three slides ; but 11. * were wholly absent. 

 The remaining two slides were barren of result. These conclusions 

 were confirmed by more prolonged research on the same slides. 



3. Five slides containing I., II.*, III., kept in a temperature of 

 121 '11 C. for ten minutes. On examination immediately after 

 heating, nothing but a still and shapeless field, with no trace of life, 

 could be seen. 



They were placed in the moist chamber. After eight hours, 

 minute moving points, which we did not venture to identify, were 

 seen in four of the slides, and a minute form of III. in one. In the 

 course of the next twelve hours, complete forms of I. and III. had 

 developed, but none of II.* Nothing appeared in the other one ; it 

 was barren to the last. 



4. Six shdes, containmg I., II.*, III., were heated up to 148 • 88 

 C. Kesults as before on fu-st examination. After eleven hours a 

 minute point had been followed into a young condition of III. {vide 

 Fig. 16, PI. XL VI.), and in the course of twenty hours the young of 

 I. and III. had been followed to the adult stage or nearly so in two 

 of the slides. III. followed in the same way in one other, and the 

 other three yielded no definite results; development appeared to 

 commence, but not continue. 



These are only typical results of a larger series of experiments. 



It win be seen, then, that the two forms which emitted sporules 

 were able to survive, ly means of theh' sporules, a temperature of 

 148 '88 0., whereas the form which gave birth to minute living 

 forms only feebly survived a temperature of 82 • 22 C. ; while again, 

 the form whose sporules were too minute to be seen appears to have 

 slightly the advantage in the contest with heat. 



We are not wishful to enter into the speculative aspects of this 

 very important question, but we are tempted, in conclusion, to state 

 briefly what commends itself to us as the most probable way of 

 accounting for the above results. 



We are not inclined to attribute to the vital element of the 

 sporule the possession of any exceptional power, which will explain 

 its ability to resist such high temperatures, ^^'e the rather believe 

 that from some physical cause it has been prevented fi'om encounter- 

 ing it, by protection. 



The adult forms are undoubtedly destroyed at a temperature of 

 from 61° to 80^ C. It is not difiicult to account for this. The 

 sarcode in a perfectly fluid solution cannot escape rising to the heat 

 of the fluid ; for from the very nature of the active vital processes, 

 a constant current of liquid must be passing into and out of the 

 sarcode by imbibition and exmosis. It must follow that when the 

 temperature is too high for the continuation of the vital processes, 

 death must ensue. This temperature all experimenters concur in 



