3o8 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



pronounced as identical with Actinomyces chromogenus Gas- 

 perini. 



In making the germination tests the ordinary agar hanging- 

 block used in studying the growth of bacteria was employed, 

 using beef extract agar without salt. The maximum tempera- 

 ture for germination and growth is apparently slightly below 

 41° C. Germination is most rapid between 35° and 40.5° with 

 little difference at temperatures between these points. Below 

 this the time for germination gradually increases so that 10° C. 

 it takes 15 or more times as long as at 35°. The largest per- 

 centage of germination is usually secured at from 30° to 37° C. 

 Apparently the minimum temperature for germination lies 

 somewhere near 5° C. 



Exposure to cold weather, several degrees below zero centi 

 grade, does not always kill the parasite. The organisms in cul- 

 tures on cooked potato cylinders withstand low temperature 

 better than those in beef broth cultures. 



While temperatures from 35° to 40° C. are most favorable 

 for the germination of the gonidia, they are unfavorable for 

 long-continued growth of the organism, although at 35° a 

 stimulating effect was produced at first. Below 20° C. growth 

 is very much retarded and slow. The maximum temperature 

 for- growth is about 40.5°, the optimum 25° to 30°, and the 

 minimum about 5° C. 



Abnormal growths or involution forms were observed in 

 the cultures but apparently these were produced as the result 

 of variation in the composition of the culture media employed 

 and were not caused by unfavorable temperatures. 



