248 



THALLOPHVTES.. 



chyma of the grass generates within 6 or lo days a form of fruit which was also at one 

 time considered a pecuh'ar genus of Fungi, and called Uredo. These Uredo-fruits of 

 Puccinia graminis form narrow long red cushions beneath the epidermis of the leaves 

 and stems of Grasses ; densely crowded hymenial branches rise upon the mycelium at 

 right angles to the epidermis, and detach large ellipsoidal spores (the uredo-spores), the 

 protoplasm of which contains red granules (Fig. 170, ///, ur). These uredo-spores 

 are dispersed after the rupture of the epidermis, and germinate after some hours upon 

 the surface of the Grasses (Fig. 171, D) ; but in these they form new mycelia from which, 

 in 6 or 10 days, new uredo-fruits again arise, while the germinating filaments of the spores 



Fig. 171. — P7iccinia grammis ; A s^^erminating teleutospore /, the pro-myceliiim of which forms the sporidia sp ; B :i prd^' 

 myceHum (after Tulasne) ; C a piece of the epidermis of the lower surface of the \ea.f o( Berber is vulgaris with a jferniinating- 

 sporidiuin sp ; i its germinating filament penetrating the epidermis; D a germinating uredospore 14 hours after dissemi- 

 nation (after De Bary, /. c). 



penetrate into the interior through the stomata. While the Fungus is multiplying in 

 this manner for several generations on Grasses during the summer in its uredo-form, 

 the production of a new form of spores begins in the older uredo-fruits ; long two-celled 

 spores, the Teleuiospores, being also formed near the roundish uredo-spores (Fig. 170, 

 ///, t). The formation of uredo-spores in the uredo-fruits then entirely ceases, and 

 teleutospores only are produced (Fig. 170, //), and with them the period of vegetation 

 closes. The teleutospores persist on the grass-haulms through the winter, and do not 

 germinate till the spring ; they emit from their two cells short septate germinating 

 filaments (Fig. 171, A, B), at the ends of which, on slender branches, the Sporidia are 

 produced. These sporidia develope a new mycelium only when they germinate on the 

 surface of the leaves of the barberry ; but their mode of germination differs from that of 



