THE PHENOMENA OF SPORE-DISCHARGE 501 



the teleutospore is the first to be formed and that the other three 

 spores are formed in succession proceeding toward the basidium's 

 base. Only one minute intervened between the disappearance of 

 the apical basidiospore and its nearest neighbour, but a much longer 

 period elapsed before the last two spores were discharged. Weimer 

 states that " an abrupt side wise movement of the basidiospore was 

 always noticed several seconds previous to its discharge, and almost 

 simultaneously a bubble appeared at its base." The " bubble " 

 which he saw arise at the base of each spore just before discharge 

 was undoubtedly a watery drop excreted from the spore-hilum. 

 The " abrupt sidewise movement " of the spore may have been an 

 optical illusion arising from the rapid development of the liquid 

 drop. I myself have not observed such a movement in connection 

 with the normal discharge of basidiospores either in the Hymeno- 

 mycetes or in the Uredineae. 



Dietel confined his investigations to species of Uredineae in 

 which the teleutospores are capable of germination immediately 

 after their formation, and he expressed the view that the spore- 

 discharge phenomena might be somewhat different in species in 

 which the teleutospores require a winter resting-period before they 

 can put forth their basidia. In order to extend observations on 

 spore-discharge to teleutospores which do not germinate until 

 spring, I have examined Puccinia graminis. I have found that the 

 phenomena of spore-discharge in this species are similar to those 

 described by Dietel for other species of Puccinia in which the 

 teleutospores germinate immediately. An account of my observa- 

 tions on Puccinia graminis will now be given. ^ 



The Discharge of Basidiospores in Puccinia graminis.— At 

 the beginning of May, 1914, on the bank of the Red River at 



' I road a paper entitled : On Spore -Discharge in the Uredinrae and the H//menn- 

 wycetes at Maneliester on September 10, 1915, befoie tlie Botany .Section of the 

 Bntisli Association foi' tlie Advancement of Science (abstract in Keporl of Bri. J.v.v.. 

 IIM;). p. 730). 1 also read a jjaper entitled : Some Comparative Observations vpun 

 the Shape of the Basidia and the Mode of Spore -Discharge in the Uredineae and the Hij- 

 menovujcetes before the Botanical Society of America at Pittsburg, on December 29, 

 1917. and again before tlie Canadian Branch of the American Phytopathological 

 Society at Giielph on December 12, 1919 (abstract in Philnpalholog)/. vol. x, 1920 

 ]). 31.')). This second paper was illustrated with lantern slides and ^vith the large 

 models of straight and curved basidia described at the end of this Chapter. 



