404 Profs. Percy Frankland and Marshall Ward. 



On now examining I found the germinated bacilli had grown into 

 curiously contorted and stunted colonies, and there stopped. No 

 further growth could be observed, although I slowly lowered the 

 temperature as follows : 



Temp. 



A rodlet fixed on the scale and measured showed no departure at 

 7 P.M. from its original length, 9 //, at 5 P.M. Growth was impossible, 

 apparently, under these conditions. 



I presume that what occurred was, germination was effected, but, 

 at the temperature 30 31 C., the delicate young rodlets could not 

 assimilate food-materials from this weak gelatine. 



Later considerations, based on further experience, suggests that 

 the variations of temperature may have combined to inhibit the 

 growth also. 



On reviewing these curves of growth at various temperatures, kept 

 approximately constant in each case, in the weak gelatine, we find 

 the following facts come out : 



1. As was to be expected, the doubling periods are longer at lower 

 temperatures than at higher ones. 



2. There are indications of a temperature near 25 C. being more 

 favourable than any others, i.e., an optimum temperature, as con- 

 trasted with less favourable lower temperatures nearer a minimum, or 

 higher ones nearer a maximum. 



3. Some facts point to the necessity for distinguishing the germinal 

 phase of growth from the more independent growth which occurs 

 after the rodlet is entirely free of the spore and its reserves. 



4. The doubling period is evidently affected not only by the mean 

 temperature employed, but by variations above and below this mean ; 

 and this in two 'ways: (1) according to the rapidity of these varia- 

 tions, and (2) according to their range. 



It is hardly worth while making any more general statements 

 until we have examined other cases, so I now pass to cultures in 

 broth. 



B. Cultures in Broth. 



On July 23 a broth-culture of spores was started in the Sachs' box, 

 darkened, at 1.30. The temperature was 17'2, and remained steadily 



