Sonic Saprophyiic Fungi of Potatoes. G. H. PetJiyhridgc. 109 



a portion of one of these bodies is illustrated in Fig. 8, Plate III. 

 The ripe spores are easily washed away but four detached ones 

 are shown. 



The once or twice septate conidiophores are arranged in a 

 vertical palisade-like fashion and are absent when the "sclero- 

 tia" first emerge. They are usually simple, but a few branched 

 ones have been observed. The setae are i- to 3-septate. 



The conidia are elongated, cylindrical, or slightly spindle- 

 shaped, with somewhat bluntly pointed ends. Their size 

 varies, but averages 2i/x x 3/x. They are hyaline and contain 

 either one central vacuole, or two situated towards the ends. 

 They germinate by producing a germ tube from near one end ; 

 and after germination many of them, but by no means all, 

 develop a transverse septum and become two-celled. After a 

 few days' growth the mycelium produced gives rise to conidia 

 borne on the ends of short branches and similar to those already 

 described. 



From a single conidium a pure culture was raised and sub- 

 cultures were made on several different kinds of media. The 

 mycelium produced is at first hyaline and alrnost wholly 

 submerged. Old mycelium is smoke-coloured and bears 

 appressoria (see Fig. 7, Plate III). A striking characteristic 

 of all the cultures was the development of a beautiful amethys- 

 tine fluorescence throughout the medium. After about a 

 week's growth the development of the black bodies (always 

 bearing setae) begins ; and they are always produced in a series 

 of concentric zones which are circular in Petri dishes, and oval 

 on slants in test tubes. After a time many of these bodies 

 produce on their surfaces the amethyst-coloured globule of 

 conidia already described. The fungus thus produces conidia 

 directly from the mycelium and also in fructifications of the 

 Colletotrichum type. No other form of fructification appeared 

 in the cultures. Its chief characters may be summarised as 

 follows : 



Colletotrichum tabificum (Hallier pro parte) Pethybridge. 



Acervulis gregariis, primo sub-epidermicis, demum erum- 

 pentibus, atris, ioo-270yu, ; conidiis continuis, cylindricis vel 

 sub-fusiformibus, hyalinis, multitudine aggregata amethystinis 

 apicibus abrupte aculeatis, ^yt, x 2i/x; basidiis fasciculatis, 

 cylindricis, 1-2 septatis, 20-30jLt longis; setulis simplicibus, 

 erectis, 1-3 septatis, atris 100-340 /x longis; appressoriis atro- 

 fuligineis. 



Hab. In stirpibus subterraneis mortuis, vel paene mortuis 

 Solani tuherosi, in Hibernia. 



Healthy living potato stalks and tubers were inoculated 



