92 British UrcdinecE and Ustilao^inecE 



the conidia reproduce themselves im from fifteen to twenty 

 days. The teleutospores are developed in spherical dila- 

 tations, in the continuity of the mycelial tubes, rarel)' 

 at the ends of branches. Conjugation between conidia 

 sometimes takes place. The conidiophores emerge either 

 through the stomata or between the epidermal cells. 

 The conidia germinate more rapidly and throw out larger 

 germ-tubes when this process takes place on the living 

 leaves of the host-plant than when it does so in water. 

 This may be in part due to the more abundant supply of 

 oxygen which they would receive in the former situation. 



E. canescens. — Schroter * finds the spores germinate as 

 soon as they are ripe by protruding a germ-tube, from 20 

 to 30^ long, and 4;u wide, on the end of which a tuft of 

 cylindrico-fusiform spores are produced. The}- measure 

 from 25 to 40/J in length, and from 2"5 to 3/^ in thickness. 



Doassansia. — The germination of this genus is identi- 

 cal with that of its ally, Entyloma, consisting in the pro- 

 trusion of a promycelium of limited growth, which develops 

 apically a tuft of promycelial spores.f In D. alisviatis the 

 promycelial spores are long and cylindrical, and the}' are 

 produced in great numbers (Plate VIII. Fig. 5). 



The process is also similar in D. sagittaricr, as observed 

 by Fisch,:]: who observed conjugation to take place between 

 the fallen-off promycelial spores. He found that the germ- 

 tubes of these spores entered the sides of the cells of the 

 host-plant, having insinuated themselves between the 

 epidermal cells. The teleutospores of D. oJisviatis germi- 

 nated as soon as they were ripe, but those of D. sagittaria 

 did not do so until the ensuing spring. 



* Schroter, "Colin Beitrage," vol. ii, (1877), p. 372. 

 t Cornu, A7in. dcs Scicnc. A^at. Bof., 6'' ser., tome xv. p. 281. 

 X Fisch, " Entwickekmgsgeschichte von Doassansia Sagittarius, " Bericlitc 

 der dctitsclieu Iwlan. Gese/lsc/ta/t,'^ September, 1882, bd. ii. t. x. 



