244 RESEARCHES ON FUNGI 



grown ; while at b is shown another basidiospore which, within the 

 last 20 seconds, has excreted a drop of liquid at its hilum. The 

 drop is now of full size and the spore should be shot away within 

 the next two seconds: A series of abnormalities is shown in 

 connexion with the basidiospores c-h. 



At c in Fig. 118, drop-excretion began normally but, instead of 

 the spore and drop being shot away when the drop had attained full 

 size, the drop continued to grow and became larger and larger until 

 it ran up the spore. The drop may cease to grow when it has 

 become as great as that shown on the spore at c, or it may continue 

 to enlarge by further excretion from the spore-hilum until it forms 

 a perfect sphere 16-20 /x in diameter, as represented at d. The drop 

 then completely encloses the spore and hides it from view. Basidio- 

 spores which bear drops like those shown at c and d are never 

 violently discharged from their sterigmata ; but, subsequently, either 

 before the drop has evaporated as shown at e or after it has evaporated 

 as shown at/, they may germinate in situ. A spore which has borne 

 an abnormally large drop may germinate either apically as shown 

 at e and/ or basally as shown at g. Sometimes a spore, after attain- 

 ing full size in the normal manner, may fail to excrete a drop. Such 

 a spore, e.g. the one shown at h, is never discharged violently from 

 its sterigma. It may germinate apically, in which case it resembles 

 the spore shown at / or it may remain unchanged on the top of its 

 sterigma for many hours or even as long as three days. 



The abnormalities of the basidiospore-discharge mechanism just 

 described for Tilletia tritici closely resemble the abnormalities in the 

 same mechanism which are known to occur in the Hymenomycetes, 

 the Uredineae, and the genus Sporobolomyces. Thus excessive 

 excretion of drops correlated with an absence of violent spore-dis- 

 charge has been illustrated : by Buller for the basidiospores of 

 Psalliota campestris J and Coprinus sterquilinus 2 in the Hymeno- 

 mycetes ; by Buller for Puccinia graminis 3 in the Uredineae ; and 

 by Kluyver and van Niel 4 for Sporobolomyces salmonicolor, and by 



1 These Researches, Vol. Ill, 1924, p. 508, Fig. 205, D-G. 



2 Ibid., p. 250, Fig. 106. 3 Ibid., p. 508, Fig. 205, A. 



4 A. J. Kluyver and C. B. van Niel, " Uber Spiegelbilder erzeugende Hefenarten 

 und die neue Hefengattung Sporobolomyces," Centralb. f. Bakteriologie, Abt. 2, 

 Bd. LXIII, 1924-25, p. 16, Taf. I, Fig. 12. 



