350 



Profs. Percy Frankland and Marshall Ward. 



exposed a few hoars later as the early dawn brings the light on them 

 once more. So that even if it were true that the bacillus is safe as 

 soon as it has germinated, it would still be the case that only those 

 spores which lurk in the shadows, or are rolled by the river into unex- 

 posed places, could recover.' 



We shall see later on, however, that this action of light on the 

 spores in water is favoured by the low temperatures to which the 

 river organisms are usually subjected for subsequent experiments 

 show very clearly that whatever resisting action they may be sup- 

 posed to have is put in abeyance when the temperature is too low 

 for active and rapid growth. 



To test the germinating power of the spores after baking, or, 

 rather, drying at high temperatures, I proceeded as follows : 



A number of cover-slip preparations were made in the ordinary 

 way, with spores distributed in distilled sterile water, and these were 

 placed, infected side upwards, in Petri dishes, and exposed to 80 C. 

 in the hot air sterilizer, and allowed to cool slowly (two hours) to 

 30 C. 



The results show clearly that the germinating power of these 

 spores dried at high temperatures is by no means destroyed by the 

 high temperatures to which they are subjected. 



In the series selected the spores were distributed on the slips at 

 10 A.M., and at once put into the hot-air steriliser at 80 C. At 12 

 noon they had cooled to just below 30 C., and each slip received a 

 drop of broth-gelatine, and was arranged as the roof to a cell, the 

 culture being now a hanging drop. 



I take three of them, labelled 1, 2, and D. Nos, 1 and 2 were at 

 once put into the incubator at 21 C. ; this was 12.15 P.M. D was 

 kept dry in diffuse light at 20 till 4 P.M., and then put in as the 

 others. 



