4 Transactions of the Society. 



I have felt increasingly ever since, that their defect was that they 

 were made on the germs in what was practically a dry heat. No 

 doubt a moist heat was endured for a little while, during the 

 process of the evaporation of the fluid in which they were contained ; 

 but the critical temperature was endured without question in a dry 

 condition. It is well known that organic forms can endure this 

 much more successfully than heat endured when they are immersed 

 in a fluid. This has been well illustrated in the case of vegetable 

 seeds. Moreover, the death-point of the adult monad has been 

 very accurately determined, but the determination of this has been 

 efiected by means of fluid heat. So that it is plain enough that the 

 same conditions had not been observed in reference to the germ. 

 This, however, was never contended : it was merely afiirmed that 

 by the process employed it was sufficiently plain that the germ had 

 a heat-resisting capacity far in excess of the mature organism. 



It is none the less manifest that it would be important if pos- 

 sible to extend the researches to a discovery of the actual effect 

 upon these germs of heat endured in fluid. But the difficulties to 

 be encountered must be clearly understood. What we want to 

 decide is whether the germ of a given monad, which has actually 

 been seen to be poured out in normal conditions, can germinate after 

 a certain exposure to heat, when the germ is immersed in a fluid ; 

 and if so, what is the limit of temperature. 



Now Dr. Bastian thinks this a matter quite easy of accomplish- 

 ment ! * I have elsewhere expressed my surprise at his view of this 

 matter ; t for certainly it indicates the omission of an important 

 factor in reaching an accurate conclusion. It is, of course, well 

 known that the germs of these and similar organisms are emitted 

 from the sac into a fluid which favours, perhaps excites, immediate 

 germination. But it is a fact of the greatest importance to the 

 student of these organisms, that when these extremely minute 

 organic atoms are first emitted from the sac, they are in the 

 majority of cases relatively quite opaque ; but in the course of from 

 thirty to sixty minutes, all opacity is gone, and the minute 

 growing particle becomes distinctly oval and transparent, having a 

 very slight yellowish or yellowish-brown colour, but transmitting the 

 light more readily than the fluid in which it is contained. But 

 as this change is absolutely correlated with increase of size, 

 and sometimes of form, it becomes plain that it is a direct result 

 oi germination. Now to all who take into account everything 

 that must be considered to form an accurate judgment on this 

 question, it must be palpable that the power of a given organism 



* " Conditions favouring Fermentation," &c., ' Joum. Linn. Soc. (Zool.),' xiv. 

 p. 78. 



t " On the Life-liistory of a Minute Septic Orgauiam," ' Proc. Roy. Soc.,' 

 xxvii. (1878) p. 332. 



