MOLD OK HYPHOMYCETE GROUP 397 



the best development the medium should be slight ly acid. It 

 develops readily upon potato and bread. Colonies become visible 

 in a day, usually as tiny, white, cottony growths, which, within 

 n few days, turn green, due to the formation of the spores of that 

 color. 



Physiology. The Aspergillus fumigatus is an aerobe. The 

 optimum growth temperature is from 35 to 40. According to 

 Mohler and Buckley, growth occurs, but spores do not form 

 below 20. The spores are resistant to high temperatures. They 

 have been found to survive an exposure of seven hours at 65. 



Fig. 174. Aspergillus fumigatus from a culture on agar (Frankel and Pfeiffer). 



Twelve hours' contact with a 5 per cent, solution of phenol is not 

 sufficient certainly to destroy them. They can withstand desicca- 

 tion indefinitely. 



Pathogenesis. Experimental Evidence. The organism pro- 

 duces death within a few hours or days when injected intravenously 

 or intrathoracically into the chicken. The pigeon is particularly 

 susceptible to injections. Rabbits and guinea-pigs likewise suc- 

 cumb, usually from a generalized infection. There is sufficient 

 experimental evidence to justify the conclusion that Aspergillus 

 fumigatus may produce a primary and fatal infection in man}' 

 animals. 



