BASIDIOMYCETES. 147 



In Gymnosporangium, two kinds of teleutospores are found (distinguished 

 by their size and thickness of exospore). In many species of Puccinia, the 

 form of the teleutospores varies very much, so that in the same layer spores 

 have been observed with the characteristic form of other, allied genera. The 

 teleutospores of Endophylltim resemble aecidiospores, since they are united 

 in chains, whose cells are easily separated, and are produced in the interior of 

 a " peridium." The rnulticellular teleutospores of Coleosporium function as 

 basidia, and from each cell immediately produce basidiospores. The teleuto- 

 spores of Coleosporium and Chrysomyxa, differ from other teleutospores in the 

 absence of exospore and germ-pore. 



The ^CIDOSPORES (Spring -spores') are produced in chains which 

 are generally enclosed in an envelope of hyphse, the peridium ; the 

 peridium enclosing the spores being termed the cecidium. The 

 secidiospores are unicellular, and generally of an orange colour ; 

 they are often separated by intermediate cells which wither and so 

 assist in the distribution of the spores. The exospore is made up 

 of minute, radially arranged rods. Generally germination proceeds 

 immediately, the eecidiospore producing a germ-tube, which de- 

 velopes into a mycelium bearing either uredo- or teleuto-spores. 



The aecidia of many Rust-Fungi were formerly considered as distinct genera. 

 The aecidia of Phragmidium, Triphraymium, and Melampsora, in which the 

 peridium is wanting, were in part considered as Cteoma. The ascidia with 

 fimbriate edge, or those of Gymnosporangium with longitudinal lattice-like 

 splits, were considered as " Ecestelia " (Lattice-Bust) ; large, sac-shaped ascidia 

 on the Conifer were known as Peridermium. 



The UREDOSPOKES (Summer- spores') are unicellular and arise 

 singly, seldom in chains (Coleosporiuni). Their colourless, warty 

 exospore bears, in the equatorial plane, 2-8 germ-pores. In the 

 majority, germination proceeds immediately, and a mycelium is 

 produced which at first gives rise to uredospores and afterwards 

 to teleutospores. 



The uredospore-formations of Melampsorella and Cronartium are enclosed in 

 an envelope, and hence resemhle a^cidia. Between the uredospores sterile, 

 unicellular hyphse (paraphyses) may be found. 



The spermogonia are spherical or pear-shaped 

 generally embedded in the substratum, and are produced before 

 the ascidia, before or simultaneously with the uredospores, or before 

 the teleutospores. The conidia, as far as observations go, do not 

 generally germinate under ordinary conditions. 



Among the Rust-Fungi some species are found which only 

 form basidiospores and teleutospores (Puwinia malvacearum, 



