GERMINATION AND GROWTH. 151 



TTstilago 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 



white pustules, and which De FIG. 90. Pseudospore of UHilago recfp- 

 Bary terms conidia, which are ^culorum in germination, and secondary 

 . , . , . , . . 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 



obtuse papilla resembling the 



neck of a bottle. This is filled 



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 PIG. 91. Conidia and zoospores of Cy- 



-. i j . . . topus Candidas ; a. conidium with the 



polyhedriC portions, each pre- plasma divided ; b. zoospores escaping ; 



senting a little 



Vacuole in the Centre (a). Soon their cm *> com mencing 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 (b). These are zoospores, 



* De Bary, " Recherches," &c. in " Annales des Sciences Naturelles " (4^ 

 se"r.), xx. p. 5 ; Cooke in " Pop Sci. Rev." iii. (1864), p. 459. 



