40 



PHYSIOLOGY OF THE FUNGI 



Fig. 6. Saccharomyces cerevisine, camera lucida drawings of cells from agar cultures. 

 A, culture treated with penicillin; B, culture treated with penicillin plus cysteine. 

 (Courtesy of Nickerson and Van Rij, Biochim. et Biophijs. Acta 3: 461-475, 1949. 

 Published by permission of Elsevier Book Company, Inc.) 



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A B 



Fig. 7. The effect of hydrogen-ion concentration on the morphology of cells of 

 Sordaria fimicola. A, rounded swollen cells produced in glucose-casein hydrolysate 

 medium at initial pH 3.6. B, normal mycelium from the same culture a few days 

 after a drop of NaOH was added. 



Hum in culture. Blastomyces dermatitidis and B. hrasiliensis exhibit 

 thermal dimorphi.sm (Nickerson and Edwards, 1949). When these fungi 

 are cultured on certain media at 37°C., they are yeast-like, while at lower 

 temperatures of incubation they form mycelium. This change in mor- 

 phology is accompanied by changes in the rate of respiration and type of 



