258 RESEARCHES ON FUNGI 



Following up the clue given by Tilletia tritici, it was observed that 

 the large conidia of the phycomycetous species Conidiobolus villosus 1 

 are actively produced and discharged from an agar medium just as 

 long as the medium contains any available water. A Petri-dish 

 culture of C. villosus, exposed to dry air in the same manner as the 

 Tilletia tritici culture, continued to produce and discharge conidia 

 for 48 hours, at the end of which time the agar medium had become 

 reduced to a mere parchment. Doubtless the mycelia of many 

 other fungi, when growing on a moist substratum with their surface 

 hyphae exposed to dry air, produce and liberate their spores as freely 

 as Tilletia tritici and Conidiobolus villosus. In this connexion, as 

 bearing upon the production and liberation of spores in the Uredineae 

 and the Hymenomycetes in dry air, it may be recalled that Zalewski 2 

 found that aecidiospores are shot out of their aecidia in dry air as 

 well as in moist, although not so freely, and that Buller 3 has formu- 

 lated the general conclusion that, in the Hymenomycetes : "so 

 long as a fruit-body has sufficient moisture in itself the dryness or 

 dampness of the atmosphere without makes no appreciable difference 

 to the rate of spore-discharge." 



The Germination of Basidiospores. — Freshly discharged basidio- 

 spores, which have not been allowed to dry up during their fall or 

 afterwards, germinate very readily at ordinary room temperatures 

 in a film of moisture or on agar media. Germination, under these 

 conditions, begins within an hour of discharge and, within a few 

 hours, one finds that 100 per cent, of the spores have germinated. 

 The viability of the basidiospores of Tilletia tritici, therefore, is 

 very great. 



Freshly discharged basidiospores, which have dried up during 

 their fall or afterwards, when placed in water or under moist con- 

 ditions, never germinate. With upwards of a dozen dry spore-deposits, 

 made at different times, in which there were tens of thousands of 



1 A pure culture of this fungus, Conidiobolus villosus Martin, was kindly sent 

 to one of us (A. H. R. B.) by its discoverer, Professor G. W. Martin, from Iowa 

 State University. In the cultures exposed to dry air the conidiophores were much 

 shorter than in cultures exposed to moist air. 



2 A. Zalewski, " Uber Sporenabschnurung und Sporenabfallen bei den Pilzen," 

 Flora, Jahrg. LXVI, 1883, pp. 268-270. 



3 A. H. R. Buller, Researches on Fungi, Vol. I, 1909, p. 123. 



