156 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



malt extract media adjusted to different H-ion concentrations, 

 found that although distinct variations were present, the 4 fungi 

 responded in much the same way. The limiting P H value ap- 

 peared to be near 1.7, though very little growth occurred below 

 P H 2.2. Maximum growth was obtained at about P H 3. 



Zeller, Schmitz, and Duggar ('19) grew 12 species of wood- 

 rotting fungi on 6 kinds of culture solutions. The data obtained 

 show that vigor of growth, limiting H-ion concentration, and 

 direction of shift of the P H during growth depended both upon 

 the fungus and the culture medium. These workers thought it 

 inadvisable to formulate any general statement purporting to 

 express the relation between hydrogen-ion concentration of the 

 culture media and growth of wood-destroying fungi as a group. 



Armstrong ('21) studied sulphur nutrition of fungi on a medium 

 containing inorganic salts and sucrose. Comparing the average 

 of several different determinations, he obtained better growth of 

 Aspergillus niger, Penicillium cyclopium, and Botrytis cinerea at 

 P H 4.1 than at 5.5. When Na 2 S*0 3 was substituted for MgS0 4 , 

 A. niger and B. cinerea grew best at P H 5.9 and P. cyclopium at 

 P H 4.2, within a range of 4.2 -7.1 Changes of H-ion concen- 

 tration during growth varied with the organism and the culture 

 solution. 



Karrer ('21), using Czapek's solution in which soluble starch 

 had been substituted for most of the sucrose, found no growth of 

 Fusarium at P H 2 and approximately equal growth between 

 Ph 3 and 9.2. C olletotrichum Gossypii exhibited fair growth from 

 P H 3-4.5 to beyond 9.2. Both fungi caused a shift of reaction 

 of the culture solution, the change, except for the most alkaline 

 cultures, being in the direction of increased alkalinity. 



Kirby ('22) found that Ophiobolus cariceti requires a condition 

 of alkalinity for optimum growth on agar media. On corn meal 

 agar growth began at P H 4.5, reached a maximum at 8.1, and was 

 still good at 9.2. On potato agar growth began at P H 3.2 and 

 attained a maximum at 9. For Fusarium moniliforme on corn 

 meal agar, the range of growth was found to be greater than 

 P H 3.2-9.2, the maximum occurring near 8.2. 



Hopkins ('22) found that the growth of C olletotrichum lin&e- 

 muthianum on potato dextrose agar adjusted to different H-ion 



