Ethel M. Doidge 423 



Uschinshjs solution. There is no growth in this medium; it was 

 kept under observation for 20 days. 



Cohn's solution. No growth. 



Egg albumen medium containing 1 gm. of powdered egg albumen 

 and 50 c.c. of a -05 per cent, solution of potassium phosphate became 

 well clouded, but there was no ring or pellicle formation and no dis- 

 colouration of the medium. 



Fermi's solution becomes lightly clouded on the second day. Growth 

 proceeds slowly and after about three weeks there is a good ring above 

 the medium, and considerable sediment at the bottom of the tube. This 

 is Naples yellow in colour and very viscid, rising in a spiral swirl when 

 the tube is rotated. 



Cabbage broth clouds fairly heavily: a ring forms above the medium 

 and there is some indication of pellicle formation ; there is also a sediment 

 at the bottom of the tube. 



Milk shows no change until the third day; separation of the whey 

 takes place slowly in such a way that there is an increasing quantity of 

 clear yellowish whey at the surface, and the lower part of the tube is 

 filled with whitish minute flocculent particles. The clot is not coagulated, 

 and is slowly digested, but had not completely disappeared in cultures 

 which had been under observation for some weeks. The whey is clear 

 and yellowish in colour. 



In litmus milk the colour is partially reduced, and the culture 

 becomes slightly more acid than the control. In flasks, where a greater 

 part of the medium is exposed to the air the action of the bacterium is 

 considerably more rapid than in tubes. 



Physical and Biochemical Relations. 



Proteolytic activity in milk. In describing the cultural characters of 

 the organism, it has been stated that milk is slowly peptonised. A number 

 of flasks each containing 50 c.c. of milk were tested at intervals of five 

 days for peptone, tyrosine and tryptophane. At the end of five and ten 

 days at 30° C. the culture fluid gave positive reactions for each of these 

 compounds. In each case the reaction was stronger on the 15th and 

 20th day, particularly in the case of tyrosin for which an intense reaction 

 was obtained on the 20th day. There was also a strong reaction for 

 peptone on the 20th day. 



A similar set of flasks was tested quantitatively for the production 

 of amino-acids and ammonia. The following figures give the results 

 from one such experiment. 



