122 Mortier F. Barrus 



found that the fungus died in culture at Baton Rouge, Louisiana, during 

 the summer, even when frequently transferred to fresh media, and later 

 (1915) showed that the temperature requirements for this fungus are 

 lower than for other anthracnose fungi, the optimum being about 22° 

 to 23° C. though there is but little difference in growth between 19° and 

 26°. Edgerton gives the maximum as about 30° or 31° C. The growth 

 at optimum temperatures is between 3 and 4 millimeters a day. Muneie 

 (1917:9-11), after subjecting test-tube cultures of old mycelium to a 

 water bath at 65° C. for ten minutes, found that good growth could yet 

 be obtained but that the thermal death point of young mycelium lies 

 between 50° and 52.5° C. and that of spores between 45° and 48° C. 



The writer endeavored to determine the minimum, optimum, and 

 maximum temperatures for growth and production of spores. Potato 

 agar plate cultures of two physiologically different strains of Collet otrichum 

 lindemuihianum were kept for a few days at 25° C, after which blocks 

 of agar 3 millimeters in diameter of each strain were transferred to plates 

 of potato agar and corn agar and to tubes of sterilized bean pods. The 

 temperatures (centigrade) at which the cultures were placed were, 

 respectively, 0°, 4°, 10°, 16°, 22°, 28°, 34°, 40°, 43°. Two cultures of each 

 strain in potato agar and two of each in corn agar were placed at each 

 of these temperatures on April 8, 1914. The growth made by them is 

 shown graphically in figure 12. 



It is seen that the average growth during the first six days was less 

 than on the eight succeeding days at the temperatures 4° and 10° C, 

 but was greater at temperatures above 28° C. Growth was probably 

 checked during the first day or two at the lower temperatures by an 

 abrupt transfer from a warm room, but was resumed to some extent later. 

 While the growth was no doubt checked by the transfer to the higher 

 temperatures, and ceased altogether after a few days at 34° and above, 

 yet some growth was possible during the first day or two because the 

 temperatures then ranged between room temperature, at which the cultures 

 were started, and the higher temperatures. The figures giving the average 

 growth on the eight days following the first six represent more nearly 

 accurately the actual growth that occurs at these temperatures under 

 these conditions. Considering, then, the curve representing such growth, 

 it appears that the minimum temperature for growth lies at 0°, the 

 optimum at 22°, and the maximum at 34°. As a matter of fact, the 



