GENERAL SUMMARY 581 



In the Uredineae and the Hymenomycetes, from the point of view of 

 function : (1) the four basidiospores leave the basidium in succession • 

 (2) the spores are violently shot into the air to a distance of about 

 • 1-1-0 mm. ; (3) some 5-40 seconds before a basidiospore is shot away 

 a small drop of fluid always begins to be formed at the spore-hilum and 

 the drop grows m size and attains a diameter equal to from one-third 

 to the whole of the diameter of the spore ; (4) as soon as the drop has 

 attained its normal maximum size, the basidiospore is shot away with 

 the drop chngmg to its surface ; (5) after the discharge of a spore the 

 sterigma does not immediately collapse, nor does it bear a drop of water 

 or other substance at its summit ; and (6) the basidium-body does not 

 collapse immediately as a result of the discharge of its spores. 



The basidiospores of the Uredineae, as compared with those of the 

 Hymenomycetes, (1) are usually somewhat larger in size, and (2) are 

 usually shot to a somewhat greater distance from their sterigmata 

 Moreover, (3) the water-drop excreted at the spore-hilum in the Ure- 

 dineae IS usuaUy somewhat larger and takes a few seconds longer to attain 

 maximum size than in the Hymenomycetes. 



In the Uredineae and the Hymenomycetes the drop excreted at the 

 spore-hilum may become abnormally large, and then the spore may not 

 be discharged. 



The author describes the development and the mode of discharge 

 of the basidiospores of Puccinia graminis, Endophyllum Ewphorhiae- 

 sylvaticae, and Gymnosporangium Juniperi-virginianae. 



The author favours the view that the hfe-history of Endophyllum 

 Euphorhiae-sylvaticae is simply a shortened form of a Eu-puccinia. 



Some large models for illustrating the violent discharge of spores in 

 the Uredineae and the Hymenomycetes are described. 



Chapter II.— The author compares the mechanism for the pro- 

 duction and liberation of the basidiospores in the Uredineae and the 

 Hymenomycetes. 



In the Uredineae, the absence of fruit-bodies is correlated with the 

 parasitic mode of life of the species included in the group. 



The teleutospore, as a rule, is not set free from its place of origin 

 and therefore is not itself an organ of species-dissemination, thus 

 diliering from the aecidiospore, the uredospore, and the basidiospore. 

 It is essentially a probasidium. It stores up protoplasm and is able to 

 rest for a longer or shorter time before germinating, in these respects 

 resembling a sclerotium. Its main function is to provide for the rapid 

 production of basidiospores when these can best be liberated with a 

 chance of infecting new host-plants. 



In the Uredineae the basidia are curved and the sterigmata are 

 developed on the convex side of the basidium. This causes the basidio- 

 spores to be directed away from the host-plant and toward an open 

 space with the result that, when discharge takes place, the spores are 



