Germination of Tdcutosporcs of Ustilaginccc. 93 



Urocystis. — ^The germination of Urocystis was first 

 observed by Kiihn in U. occulta* and is also described 

 by Wolff.t U. colchici was studied by Winter ; % U. ane- 

 mones, by Von Waldheim ; § U. viohe, by Prillieux ; || and 

 U. priJtitiUcola, by Pirotta.lT 



The process consists in the protrusion of a promycelium 

 from the inner coloured spores (the paler peripheral pseudo- 

 spores do not germinate), into which the protoplasm passes 

 to the upper end, where it gives rise to a variable number 

 of primary spores. If the promycelium be produced under 

 water, no spore-formation occurs until its point comes into 

 the air. The primary spores fall off, and occasionally con- 

 jugate in various ways, but not so constantly as in Tilletia ; 

 they also frequently germinate whilst attached to the pro- 

 mycelium. 



U. occulta. — The central, dark-coloured spores (as first 

 described by Kiihn**) emit a promycelium, at the apex of 

 which from two to six primary spores are borne. These 

 sometimes conjugate by a transverse bridge at their upper 

 ends, and often germinate — as Wolff has more recently 

 shown — while still attached to the promycelium, from their 

 lower ends, sending out a long, narrow germ-tube, which 

 receives the protoplasm from the interior of the spore, so 

 that the upper part of the spore is first emptied of its 



contents.ft 



U.fiscJieri. — The spores of this species, which Mr. Soppitt 

 was kind enough to send me, germinated only after a con- 



* Kiihn, loc. cit., pp. 78-80, t. ii. figs. 13-34. 

 t Wolff, "Der Brand des Getreides," pp. 16, 17, t. ii. figs. i-io. 

 X Winter, " Ustilagineen Flora" (1876), Nos. 10, II. 

 § F. von. Waldheim, loc. cit., t. vi. figs. 38-43. 



II Prillieux, Ann. des Scienc. Nat. Bot., 6'" ser., tome x. (1880), p. 49, t. i. 

 1 Pirotta, "R. Nuovo Giornale Bot. Ital.," vol. xiii., 12 Luglio (i88i), 

 No. 3. 



** Kiihn, loc. cit., t. ii. fig. 20a. 



tt Wolff, loc. cit., t. ii. B. figs. 7, 8. 



