2 68 RESEARCHES ON FUNGI 



and completed by adding to it the sterilised fragment of glass shown 

 at / in Fig. 133, A. The completed ring was then turned into an 

 upright position, set in a sterile Petri dish, and covered with a 

 sterile cover-glass (Fig. 133, B). The cover of the new dish was 

 set in place, the dish covered with a bell-jar, and the whole left at 

 room temperature for 2-3 hours. During this period, numerous 

 basidiospores were discharged more or less horizontally away from 

 the mycelium which was in a vertical plane and, after completing 

 their trajectories in the still air of the ring-chamber, they fell on to the 

 base of the Petri dish. At the end of the period allowed for spore- 

 discharge, the Petri dish together with its adherent ring was in- 

 verted, and the spore-deposit was examined with the microscope. 

 The appearance presented by one of the spore-deposits, when thus 

 magnified, is shown in Fig. 133, C. On the left can be seen the 

 mycelium growing at the surface of the agar, and toward the right 

 the spores spread out on the glass surface of the Petri dish. Below 

 is a scale in tenths of a millimetre, by the use of which one can read 

 off the distance to which any individual spore has been discharged. 

 Three separate experiments were made. 



In the experiments just described, it was found that the 

 majority of the spores had fallen at a distance of 0-4 to 0»6 mm. 

 from the outer surface of the mycelium, and that comparatively 

 few had been discharged to a distance exceeding 1-0 mm. The 

 maximum horizontal distance of discharge was 1 • 4 mm. 



The hyphal plexus of a mycelial mat of Tilletia tritici, with its 

 scores of basidiospores projecting from their sterigmata (c/. the 

 transverse section in Fig. 114, C, p. 232), is reminiscent of the 

 hymenium of the Hymenomycetes. 



The maximum horizontal distance of spore-discharge, as 

 recorded by Buller, 1 is : for the non-tremelloid Hymenomycetes, 

 0-2 mm. ; for the Tremellineae, • 65 mm. ; and for the Uredineae, 

 0-85 mm. In the three experiments with Tilletia tritici above 

 described, several spores were discharged horizontally to a distance 

 of 1-2 to 1-4 mm. We may therefore conclude that Tilletia tritici 

 discharges its basidiospores to a greater distance than any other 

 known member of the Basidiomycetes. 



1 A. H. R. Buller, Researches on Fungi, Vol. II, 1922, p. 169. 



