THE ANGULAR LEAF-SPOT OF COTTON: CAUSE 327 



growth was copious, smooth, ghstening and the color after a 

 month was mostly between Ridgway's light cadmium and his 

 empire yellow (R2), the dark stain ranging from his orange 

 citrine in the slime to his mouse gray in the potato, and all but 

 an insignificant residue of the starch was consumed. 



In peptone-beef bouillon there is a moderate and persistent 

 clouding, the best growth at first in unshaken tubes being at the 

 top. There is a pale yellow rim and a moderate maize yellow 

 precipitate. There are some pseudozoogloeae. 



It grows moderately in Uschinsky's solution with a pale rim 

 and considerable flocculence. It grows feebly or not at all in 

 Cohn's solution. 



The thermal death-point lies between 50° and 51°C. but is 

 never 50°C. (tests of 1919 in +15 peptone beef bouillon). 

 The maximum temperature lies between 36° and 38°C. — repeated 

 in 1919 it grew at 35° and not at 37° and after 14 days at 37° 

 the tubes did not cloud at room temperature (6 days) . It grows 

 slowly at 10°C. There was no growth in +15 peptone-beef 

 bouillon in 6 weeks at 8°C. Repeated in 1919 faint clouding 

 after 10 days at 8.5° to 10.5°C.; the tubes at 6° to 8°C. remained 

 clear for 21 days (as long as tested). 



Tubes of plain milk inoculated in 1919 gave after 43 days 

 the result shown in Fig. 259. At this time there were no tyrosin 

 crystals. The whey, sterilized at 54°C., or kept in the 

 thermostat at 38-44°C., caused prompt precipitation of the curd 

 when added to sterile milk and subsequent transfers from these 

 tubes to suitable media showed them to be free from bacteria. 



In litmus milk the litmus is blued and the casein is thrown 

 down slowly. The litmus may be reduced, but is not reddened, 

 so that the existence of a lab ferment is inferred. The precipi- 

 tated curd is not promptly digested but subsequently most of 

 it disappears (2 months), and tyrosin crystals not visible at 

 first (30 to 40 days) are then abundant (Fig. 260). Compare 

 with No. II (Fig. 93). 



This organism is extremely sensitive to light, even 2-minute 

 exposures (on ice) being enough to clear the sunlit one-half of 

 thickly sown agar-poured plates, and even 1 -minute exposures 



