15 



filtration 12.5 g of agar flour was added to the infusion, 

 and the mixture was steamed for one and one half hours. It 

 was then filtered again and was ready to tube and sterilize. 

 The tubes were slanted and the stock cultures were inocul- 

 ated in streaks. On this medium the fungus produces but lit- 

 tle mycelium, at or beneath the surface. The conidia are 

 borne in relatively large orange colored masses on the sur- 

 face of the medium along the streak, these acer vuli being 

 visible in from two to five days after inoculation. 



Before the spores were used in the experiments, 

 the stock cultures were allowed to grow undisturbed from 

 five to fifteen days, which insured a sufficient quantity 

 of spores from a single tube for the inoculation of an en- 

 tire series of experimental cultures. Preliminary tests 

 seemed to show that spores from ajervuli in the same tube 

 but of different ages were not at all uniform in viability. 

 Direct inoculation of the culture dishes from the spore 

 masses of the stock tubes was found to be unsatisfactory, 

 since it was not only desirable to have all cultures cont- 

 ain approximately the sane number of spores, but also that 

 the percentage of viabilityof the spores in all cultures 

 should be as nearly alike as possible. It seemed desirable 

 to av:id small pieces of agar and bits -f mycelium in the 

 liquid cultures, for such contamination might influence 

 the effect of the salts in the solutions on the germinat- 

 ion of the spores, as by adsorption or the formation of 

 new chemical compounds. Tne plan was therefore evolved of 



