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effect of the growth on the reaction of the medium is given; 

 = no change, At = change in the alkaline direction, Ac •-= 

 change in the acid direction. In the last column the intensity of 

 the symbiosis effect is given roughly in 7 different degrees, o sig- 

 nifying, effect entirely absent, 1, weak but undoubted reaction, and 

 6, the complete and typical symbiosis reaction. Each test was per- 

 formed in duplicate. 



