CH. Vlll] 



UREDINALES 



197 



of the spore forms other than the teleutospore, such as Aecidium, Caeoma 

 and Uredo, still survive in our nomenclature. 



The teleutospores (figs. 164, 165, 166) may be unicellular or they may 

 be made up of two or more cells forming a compound structure, each cell of 



Fig 165- Cronnrtimit 

 asdepiadetim Fr. ; te- 

 leutospore mass with 

 basi.iia and spores; af- 

 ter Tulasne. 



Fig. 1 66. Mdainpsora betulina Desmaz. ; germinating teleutospores ; 

 after Tulasne. 



which germinates independently. The teleutospore is simple in Uromyces, 

 Coleosporium, and Melampsora, it is two-celled in Gymnosporangium and 

 Piiccinia, it is built up of three to ten superposed cells in Phraginidmm, and 

 of a larger number in X enodochiis . In Triphragmidium it consists of three 

 cells laterally placed and in Chrysomyxa and Cronartium the simple teleuto- 

 spores are so massed together as to simulate compound forms; their real 

 nature is revealed by their early separation one from another. One-celled 

 teleutospores occur exceptionally in the two-celled species and are known 

 as mesospores. 



The teleutospores may be massed together and incrusted in the tissues 

 of the host, or they may be detached readily from their stalks and carried 

 by the wind or by other agencies. Further development may take place as 

 soon as conditions are favourable, or may be delayed till after a resting 

 period, usually till the spring following development. 



In either case the nucleus in each cell ultimately undergoes two successive 

 divisions, which constitute a meiotic phase, and the daughter nuclei are 

 separated by transverse walls, so that four uninucleate cells are produced. 

 The teleutospore-cell thus functions as a tetrasporangium and divides into 

 four portions, constituting the transversely septate basidium. From each cell 

 a short, pointed branch or sterigma arises, its end dilates, a basidiospore 



