2 Transactions of the Society. 



followed developed into the parent form. It was thus manifest that 

 in one instance of the six a germ was produced, too small to he 

 discovered on its emission from the sac by the most powerful lenses 

 at our disposal. 



In every case the demonstrated germs were followed into the 

 adult condition ; and it was then apparent that multiplication was 

 carried on to an enormous extent by " fission," which was both 

 simple (into two) and multiple (into some multiple of two). But 

 after a more or less definitely marked lapse of time the living pro- 

 cesses were rejuvenated by the equivalent of a genetic process, as 

 above stated. 



Now in the interests of an important Biological question, 

 dealing with the mode of origin of the lowest septic organisms, it 

 was of moment to determine whether these demonstrated germs 

 could resist heat better than the adults, and if so in what degree. 



The accomplishment of this is by no means an easy task. It is 

 a matter requiring great care, patience, and the education that 

 comes of repeated failure, to follow a given form through its meta- 

 morphoses into the condition of a germ-sac, and then to watch 

 until the emission of the germs is demonstrated. But to subject 

 these to varying heat conditions and subsequently study their 

 behaviour, is manifestly a matter requiring the utmost delicacy of 

 treatment. To do it at all, and obtain reliable results, the par- 

 ticular germs emitted under the eye of the investigator should be 

 exposed to the required tests, and then the results of each ex- 

 posure studied, by an observer who had familiarized himself with 

 the developmental behaviour of the germ, when not subjected to 

 the given heat conditions. In this way alone, so far as I can per- 

 ceive, could it be determined what heat conditions arrested or 

 finally destroyed the vital action of the germ. 



The only manner in which this could be done, so far at least as 

 the capacity of myself and colleague to devise extended, was to 

 demonstrate the spore emission of the several monads on separate 

 slips of glass ; and when it had taken place, instantly — whUe the 

 spore was freshly emitted — to expose it to a slowly increasing 

 temperature in air until the desired point was reached. Then to 

 slowly cool it, and remoisten the space under the cover, by capil- 

 larity, with every conceivable precaution, and then, under proper 

 conditions for preventing evaporation, to examine the "field" 

 steadily to discover whether development of the germs ensued or not.* 



* An admirable method for the introduction of sterilized pabulum, ■which should 

 always be ready at hand, was ultimately employed. It consisted in filling by 

 capillarity the delicate glass "vaccine tubes" in which the lymph is taken by 

 the physician, and kept — with pabulum proved to be suitable for the monads — 

 hermetically sealing the tubes, and then subjecting these with their contents to 

 a germ-destroying temperature in a Papin's digester. They would thus be ready 

 when required ; and on breaking the ends of these, and placing one end in con- 



