[HARRISON- ORGANISMS IN AESCULIN-BILESALT MEDIA 213 



vanderleck] 



From each plate a number of doubtful colonies were inoculated 

 into litmus milk. By doubtful colonies we mean colonies which gave 

 a light brown or hazy or faintly coloured field. The following results 

 were obtained : — 



The 8 tubes which were unchanged after 24 hours coagulated 

 in 48 hours, were plated on aesculin and gave distinct black colonies, 

 but these colonies transferred to litmus milk coagulated the milk 

 with an acid reaction followed by digestion of the casein. These 

 8 organisms are described later on and represent only one species 

 indicated provisionally as IH. It differs from the 17 varieties de- 

 scribed above and in order to obtain a definite idea of its numerical 

 prevalence in milk other samples were taken from the farmers A.L. 

 and J.D. who supplied the samples 9 and 10. The sample A.L. 

 was diluted 2,000 times and 1 c.c. poured into each of 10 aesculin 

 plates and the sample J.D. was diluted 200 times and 1 c.c. of the 

 dilution poured into each of 10 plates. After 48 hours' incubation at 

 37 °C. the following numbers of black colonies appeared: — 



Sample A. L. Colonies with large fields, 4, 1, 7, 6, 8, 5, 7, 3, 3, 4 

 " " small " 1, 6,10,10. 



Sample J.D. " « large " 6, 8, 9, 6, 5, 6, 8, 6, 4, 7. 



« « small " 13, 19, 3, 7, 6, 29, 7, 75, 9, 5. 



All large black or brown colonies were transferred to litmus 

 milk and kept at 37 °C. and also 10 small colonies from each sample 

 were put in litmus milk. . 



After 18 hours' incubation the results were as follows: — 

 Large colonies, A.L. 46 inoculated tubes all gave acid and gas. 



" " J.D. 69 " "67 " " " " 



2 showed acid and gas after 4 days . These two, transferred to fresh 

 litmus milk gave acid and gas in 16 hours. 



Of the small colonies, all produced acid but none developed gas 

 in 24 hours. 



Sec. IV, 1915—14 



