COMPACT AND LOOSE TELEUTOSPORE-SORI 543 



Compact and Loose Teleutospore-sori. — In many species of 

 Puccinia, e.g. Puccinia graminis, the teleutospore-sorus is very 

 compact : the teleutospores press against one another and thus 

 form a continuous layer. The teleutospore is two-celled and, 

 as if to make it easy for the lower cell 

 of the two to send out its basidium, 

 its germ-pore is usually situated as high 

 up in its cell-wall as possible (Fig. 

 204, A, p. 505). In Phragmidium, e.g. 

 Phragmidiuni Rubi, on the other hand, 

 the teleutospore-sorus is very loose : 

 the teleutospores do not press against 

 one another but are isolated from one 

 another (Fig. 220, b and c). This isola- 

 tion of the individual teleutospores or, 

 in other words, the provision of well- 

 developed inter-teleutosporic spaces, is 

 here of distinct advantage for the 

 dispersal of the basidiospores. The 

 teleutospores, instead of consisting of 

 two cells only, as in Puccinia, consist 

 of a row of cells, in P. Rubi 4 to 7 in 

 number ; and each cell produces a basi- 

 dium. The spatial separation of the 

 teleutospores permits of each individual 

 teleutospore producing a comparatively 

 large number of basidia which are 

 laterally situated but, nevertheless, provided with free space for 

 the successful discharge of their basidiospores. 



Spore-wall Pores. — The walls of uredinous basidiospores are 

 exceedingly thin, whilst those of teleutospores, uredospores, and, 

 aecidiospores are relatively thick. Associated with this difference 

 in wall thickness is the presence or absence of pores. The basidio- 

 spores, which have very thin walls, have no pores whatever and 

 doubtless, like thin-walled hymenomycetous basidiospores, can send 

 out a germ-tube anywhere at their surface. For a uredinous basidio- 

 spore under natural conditions the actual position in the wall for the 



Fig. 220. — Phragmidium Rubi. 

 a, a verrucose aecidiospore ; 

 6, a teleutospore with a long 

 pedicel and six cells ; c, a 

 teleutospore, boiled in lactic 

 acid for one minute, show- 

 ing 2-3 germ-pores in each 

 cell. On Rubus fruticosus. 

 From W. B. Grove's British 

 Rust Fungi. Magnification : 

 a, 600 ; b, 360 ; c, 600. 



