256 



RESEARCHES ON FUNGI 



spores, after removal of its cover, was inverted and supported on 

 two corks at a height of 4-5 cm. above the surface of a table in the 

 laboratory where the air had a relative humidity of 35 (Fig. 128). 

 A slide was placed at a distance of 1-2 cm. beneath the mycelium 

 of the culture dish, and the slide was changed at intervals as required. 

 Whether or not basidiospores continued to be discharged from the 

 mycelium could be decided by examining the slides with the micro 



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Fig. 128. — Tilletia tritici. The discharge of basidiospores in dry air. The 

 Petri dish p containing oatmeal-agar to, bearing at its surface a mycelial 

 mat, is inverted and supported on two corks c c resting on a laboratory 

 table t. A glass slide g rests on a support s about 1 cm. beneath the 

 mycelial mat. The very dry air of the laboratory (relative humidity 

 30-35) freely circulated under the Petri dish at a a. Basidiospores 

 continued to be shot away from the mycelial mat for upwards of twelve 

 hours ; and they fell downwards, as indicated by the arrows, so as to form 

 a spore-deposit on the glass slide g. Whilst they were falling, the agar 

 shrank considerably and cracked owing to loss of water by evaporation 

 (vide Fig. 129). About three-fourths the natural size. 



scope and finding out whether or not basidiospores had settled 

 upon them. 



The experiment was started at 10 o'clock in the morning and, 

 as shown by an examination of the slides, basidiospores continued 

 to be produced and discharged until 10.30 in the evening. A fresh 

 slide was then placed under the mycelium. At 10.30 next morning, 

 i.e. 24 hours after the beginning of the experiment, the slide was found 

 to bear a thin spore-deposit. That the mycelium had been exposed 

 to very dry air was shown by the fact that, at the end of the 24-hour 

 period, the agar in the plate had cracked across in the middle, the 

 breach between the two parts measuring 8 mm. in width (Fig. 129), 



