TILLETIA TRITICI 263 



Boss, 1 in 1927, as a result of his cytological studies, observed that 

 chlamydospores of Tilletia tritici produced in artificial cultures con- 

 tain one nucleus instead of two. Possibly the non-germination of 

 artificially produced chlamydospores is correlated with their haploid 

 condition. 



Spore-fall Observed by the Beam-of- Light Method. — In certain 

 Hymenomycetes growing wild, in daytime under favourable condi- 

 tions of light, clouds of spores may be observed coming away from 

 the under side of the fruit-bodies. Thus Buller, 2 by daylight, has 

 seen such clouds escaping from the pilei of Polyporus squamosus, 

 Fomes applanatus, Armillaria mellea, Pleurotus ostreatus, P. ulmarius, 

 Amanita muscaria, and Tricholoma personatum. In all Hymenomy- 

 cetes, the emission of spore-clouds from the fruit-bodies can be 

 observed in the laboratory by means of a concentrated beam of 

 light. The beam directed under active pilei of Schizophyllum com- 

 mune, Daedalea unicolor, or Psalliota campestris reveals to the eye 

 millions of escaping spores. 3 



If a strong test-tube culture (an agar slope) of Tilletia tritici is 

 inverted, the spores falling in succession slowly downwards through 

 the air in the interior of the tube are invisible in diffuse daylight, 

 but they can readily be seen when illuminated artificially. A beam 

 of light emitted by a strong incandescent lamp in a projection 

 lantern was concentrated by means of a plano-convex lens and 

 passed through the air beneath the agar in an inverted test-tube 

 culture (Fig. 131). In the narrow beam of light the individual 

 spores could be seen with the naked eye falling slowly downwards 

 as white particles. The visibility of the spores was somewhat 

 increased when the naked eye was aided with a magnifying 



glass. 



The Distance of Basidiospore-discharge.— The maximum vertical 

 distance to which the basidiospores of Tilletia tritici are shot from 

 their sterigmata in still air was determined as follows. A sub- 



1 G. Boss, " Beitrage zur Zytologie der Ustilagineen," Planta, Bd. Ill, 1927, 



pp. 619-622. 



2 A. H. R. Buller, Researches on Fungi, Vol. I, pp. 89-93 ; Vol. II, pp. 100-102, 

 133 ; Vol. Ill, pp. 480, 483-484 ; and observations hitherto unpublished. 



* A. H. R. Buller, ibid., Vol. I, pp. 102-104. 



