GERMINATION AND GROWTH. 151 
Ustilago as have been remarked in the sporules of the first 
generation in Tilletia. 
Returning to Cystopus, as the last of the Uredines, we must 
briefly recapitulate the observations made by Professor de Bary,* 
who, by the bye, claims for them an affinity with Peronospora 
(Mucedines but too well known 
in connection with the potato 
disease), and not with the Ure- 
dines and their allies. In this 
genus there are two kinds of 
reproductive organs, those pro- 
duced on the surface of the plant 
bursting through the cuticle in aie 
white pustules, and which De Fic. 90.—Pseudospore of Ustilago recep- 
Bary terms conidia, which are taculorum in germination, and secondary 
. H . spores in conjugation. (Tul.) 
generated in chains, and certain 
globose bodies termed oogonia, which are developed on the 
mycelium in the internal tissues of the foster plant. When the 
conidia are sown on water they rapidly absorb the moisture, and 
swell; the centre of one of the 
extremities soon becomes a large E>, ae 
obtuse papilla resembling the e 2 i 
neck of a bottle. This is filled j e 
with a granular protoplasm, in 
which vacuoles are formed. = 
Soon, however, these vacuoles 
disappear, and very fine lines of 
demarcation separate the pro- 
toplasm into from five to eight Fic. 91.—Conidia and zoospores of Cys- 
is 3 topus candidus,; a, conidium with the 
polyhedric portions, each pre- plasma divided; b. zoospores escaping ; 
F : ‘ ; d from the conidium; 
senting a little faintly-coloured % sities sloaperen | é souetiores, having Wek 
vacuole in the centre (a). Soon their cilia, commencing to germinate. 
after this division the papilla at the extremity swells, opens itself, 
and at the same time the five to eight bodies which had formed 
in the interior are expelled one by one (2). These are zoospores, 
*De Bary, ‘ Recherches,” &c. in ‘‘ Annales des Sciences Naturelles” (4™¢ 
sér.), xx. p. 53; Cooke in “ Pop Sci. Rev.” iii. (1864), p. 459. 
