10 Transactions of the Society. 



flagellum at the end of seventeen minutes : this increased in vigour 

 and rapidity, and was repeated by the remainder, until at the end 

 of a hundred minutes all were either swimming freely or vigorously 

 swaying their bodies. 



Temperatures of 135°, 138°, 140' and 142° Fahr. were then 

 successively tried in the same way. At 135° Fahr. five out of six 

 forms regained complete vigour from a state of total inaction in two 

 hours. At 138° Fahr. only two in eleven regained the power of 

 movement, and that but sluggishly, after six hours of watching. 

 One of the remainder had slight indications in the flagellum and 

 the body, but this ceased. At 140° Fahr. the field was absolutely 

 still for eighty minutes. A slight movement in the flagella of two 

 of the forms fixed upon was then seen ; but at the expiration of 

 eight hours there was no movement of any kind and the organisms 

 were in the position in which they were first seen. After a heating 

 to 142° Fahr. all was inaction from the first examination to the 

 end of the twelfth hour. That is to say, so far as the original set 

 of organisms were concerned there was no trace of vitality from 

 first to last. 



It was thus plain that a temperature of from 140° to 142° 

 Fahr. is absolutely destructive of the adult organism. 



Pursuing this mode of inquiry in relation to the whole of the 

 six monads as opportunity permitted, the following results were 

 reached, viz. : — 



1. Three of the organisms shown in Figs. 7, 8, and f>, Plate I., 

 and whose life-histories are given respectively in the ' Monthly 

 Microscopical Journal,' vol. x. pp. 53-58, vol. xi. pp. 7-10, and 

 vol. xii. pp. 261-270, were killed in the adult state at a temperature 

 of 140° Fahr. 



2. Two of the organisms portrayed in Figs. ] and 11, Plate I. 

 (whose histories are detailed respectively in vol. x. pp. 245-249, 

 and vol. xi. pp. 69-72 ibid.), were killed in the adult condition 

 between 140° and 142° Fahr. ; and 



3. One, the last, and largest, of these six monads, seen at 

 Fig. 12, Plate II. (an account of which is given in vol. xiii. pp. 

 185-197 ibid.), was wholly destroyed in its adult condition at 138° 

 Fahr. 



Now, between these points of temperature, viz. 138° and 142° 

 Fahr., there is little doubt but the majority of the septic organisms 

 are killed when in the mature stage. It is certainly true of these 

 forms, which are in many senses typical. 



Having ascertained this, we are prepared to study the effect of 

 higher temperatures upon the spores. 



It has been already shown that it is needful first to be quite 

 sure that the spores, in the condition required, are actually in the 

 fluid exposed to the testing temperature. Now we can only see 



