324 



PHYSIOLOGY OF THE FUNGI 



by Melanospora destruens to be influenced by the concentration and kind 

 of sugar used. Glucose, fructose, or an equimolar mixture of these 

 sugars, when used at the rate of 5 g. per hter, allowed the production of 

 perithecia, but no perithecia were formed when 50 g. was used. Many 

 perithecia were produced when 50 g. per liter of sucrose was used. 



The favorable effect of sucrose on perithecial formation was replaced 

 by various hexose phosphate esters. Glucose-1-phosphate and fructose- 

 1,6-diphosphate were equally active. In view of their ready enzymatic 

 interconvertibility in organisms, this would be expected. These results 



ABC D E 



Fig. 65. The effects of different carbon sources on the production of conidia by 

 Glomerella cingidata after 22 days on asparagine medium at 25°C. The carbon 

 sources are: A, glucose; B, sucrose; C, maltose; D, sorbose; E, starch. Note that 

 sporulation is greatest on sucrose and least on starch. 



suggest that M. destruens phosphorylates sucrose with greater ease than 

 either glucose or fructose. This is in line with the experiments of Dou- 

 doroff (1945) with growth of Pseudomonas saccharophila. Since M. 

 destruens makes better growth upon glucose than upon sucrose, it may be 

 suggested that the pathway of carbohydrate utilization is different in 

 growth and reproduction. These findings emphasize again that the 

 requirements for growth and reproduction may be different. 



Glucose, mannose, fructose, lactose, and sucrose are reported (Mix, 

 1933) as favorable for pycnidium formation by Phyllosticta solitaria. 

 Lactose was the most favorable sugar for the production of perithecia by 

 Diaporthe phaseolorum var. hatatatis (Timnick et al., 1951). Brodie (1948) 

 induced Cyathus stercoreus to produce normal, fertile fruit bodies on 

 semisynthetic media containing filter paper. 



In our laboratory we have observed that the carbon source affects 

 reproduction of a number of other fungi, and that the best source for 

 sporulation is not always the same which yields maximum vegetative 

 growth (Figs. 65 and 66). Some of these fungi with some more favorable 



