160 EFFECTS OF REACTION OF SUBSTRATE ON FUNGI 



(1928), Maclnnes (1922), Schaffnit and Meyer-Hermann (1930), 

 Sherwood (1923), and Sideris (1929). 



Schaffnit and Meyer-Hermann (1930) determined the pH 

 optima for growth of a group of soil-borne fungi as a basis for 



5.8 



6.0 



6.2 6.4 6.6 6.8 



Hydrogen -ion concentration 



.0 



7.2 



7.4 



Fig. 24. Relation of hydrogen-ion concentration to infection of cabbage 

 by Plasmodiophora brassicae. Infection is inhibited as alkalinity is ap- 

 proached. (After Chupp.) 



their field trials. From these results thev concluded that such 

 organisms may be grouped as follows: 



1 . Litrophilic: those that prefer alkaline soils, including Pythhnn 

 de baryanum, Momlwpsis aderholdii, Fusarium nivale, F. equiseti, 

 Ophiobohts graminis, and Typhula grarmneum. If the soils are 



