157 



These experiments were made by inoculating plates (made in 

 March with haemolysed blood; in November, with pepsindigested 

 blood) with fresh cultures of the different strains and then putting 

 them in an air thermostat. A thermometer controlling the tempe- 

 rature, was placed by the side of the plates. 



In experiment „I" the temperature was only about 23° for a 

 large part of the time on account of faulty regulation, while the 

 opposite happened in experiment „II" and the experiment at 26° 

 in March, where it was about 1° higher than the temperature given, 

 for a few hours. 



The two last experiments in March , were inadvertently only 

 continued for about IV2 days, while the plates in the other cxperi 

 ments remained in the incubator for 5 days. 



In spite of these technical deficiencies all the experiments are 

 given as I do not consider the results obtained in March 1920 

 to the absolutely worthless. 



The growth was estimated in different degrees; (1) = trace, 

 1 = weak, 2 = fairly good, 3 = luxuriant growth. 



In cases where weak or absent growth occurred it cannot be 

 due to the inoculation of too few living organisms because the 

 weak growth in the great majority of cases consisted of a confluent 

 mass of growth, not of isolated colonies. 



It will be seen that the minimal growth temperature for the 

 different cultures examined is not the same, but varies between 

 20° and 25°. The individual differences between the strains 

 are particularly prominent in the 23°-experiment. 



That these variations do not depend upon the exposure of the 

 strains actually to different temperatures is evident from the fact 

 that strains inoculated on the same plate (about 10 cm. in diame- 

 ter) were just as different from one another, as those on different 

 plates in the same experiment. That we are dealing with fairly 

 constant individual characters of the strains is rendered probable 



