210 RESEARCHES ON FUNGI 



discharge, the drop and the spore cling together and are shot to a 

 distance, varying with the species, from about 0*1 mm. to 1 -0 mm. 



Buller was struck by the great resemblance of the sterigma and 

 sickle-shaped secondary conidium of Tilletia tritici, as illustrated by 

 Brefeld, 1 to the sterigma and basidiospore of the Hymenomycetes, 

 the Uredineae, and the species of Sporobolomyces, and he therefore 

 thought it probable that a secondary conidium of T. tritici is shot 

 violently away from its sterigma by the drop-excretion mechanism. 

 Working in conjunction with Buller, Vanterpool undertook to test 

 this supposition, with the result that violent discharge of the 

 secondary conidia with drop-excretion was actually observed. As 

 a result of this discovery, Buller and Vanterpool came to the 

 following important theoretical conclusions : (1) new and weighty 

 evidence confirming the view that the Tilletiaceae belong to the 

 great group of the Basidiomycetes has been obtained ; (2) the so- 

 called secondary conidia of Tilletia tritici are true basidiospores ; 

 and (3) the so-called primary conidia are morphologically equivalent 

 to sterigmata. A brief communication embodying these conclusions 

 was published in Nature in December, 1925. 2 



Normally, under proper conditions of ventilation in cultures and 

 doubtless under natural conditions in the open, the secondary 

 conidia of Tilletia tritici and of other species of Tilletia are shot 

 away from their sterigmata as soon as they become mature, and 

 they germinate only after they have been discharged. Brefeld, in 

 his illustrations, 3 shows secondary conidia of T. tritici, T. decipiens, 

 T. controversa, and T. zonata germinating in situ, i.e. whilst still 

 attached to the sterigmata on which they developed. This kind 

 of germination, which will be treated of later (vide Figs. 109, A, 

 p. 223, and 118, e, /, and g, p. 243), is abnormal— a fact which 

 Brefeld did not realise. The failure of Brefeld and of others to 

 observe the violent discharge of the secondary conidia of T. tritici, 



1 O. Brefeld, Untersuchungen iiber Pilze, Heft V, Leipzig, 1883, Plate XII, 

 Figs. 26, 31-34 ; Plate XIII, Figs. 35-15. Vide also Brefeld's figures of secondary 

 conidia reproduced by F. von Tavel in his Vergleichende Morphologie der Pilze, 

 Jena, 1892, Fig. 53, p. 117. 



2 A. H. R. Buller and T. C. Vanterpool, " Violent Spore-discharge in Tilletia 

 tritici," Nature, Vol. CXVI, 1925, pp. 934-935. 



3 O. Brefeld, loc. cit. : Heft V, 1883, Plate XII, Figs. 31a, 32, and 33, Plate XIII, 

 Fig. 43 ; Heft XII, 1895, Plate X, Figs. 1, 2, 4, and 6. 



