This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...the appearance of the cultures is frequently markedly different from the more slowly growing ones at room temperatures. It seems to me that we should subject the organism used in such studies to approximately the same temperature conditions to which it is exposed in nature rather than to temperatures which are decidedly abnormal to the fungus. It seems that the growth of Aspergillus at 25C. may be more fittingly termed "normal1 than the growth which the mold may make at a temperature of 34C, For this reason all of my cultures were either grown in the dark at room temperatures fluctuating between 20 and 22C., approximately, or at a constant temperature of 25C. i« Duration of the experiments. The time factor of a culture greatly influences it3 dry weight yield. The dry weight of a culture should, without question, be deter mined at the moment the maximum growth is obtained, for shortly after this time the fundus will begin to lose weight due to autolysis. The time required for the production of maximum dry weight depdnds upon the species, age of spores, temperature, etc., and perhaps changes with each variation in the composition of nutrient solution. In experiments involving many different concentrations of a given salt in the nutrient medium, it is obviouB that certain arbitrary time periods must be established, altho it is recognized that such time periods may not correspond to the point of maximum yield of all the different series of cultures involved. Since the cultures on the standard nutrient solution (hereafter spoken of as "standard cultures") have been found to attain their maximum growth in 10 days at the temperature prevailing. It was decided to make dry weight determinations of all the cultures at this time. In view of the slo...