FIR ST GROUP. THA LL OPHYTES. 



fresh spores by abjunction ; the spores, at first polyhedral from mutual pressure, become 

 afterwards round and separate from one another at the mouth of the cup (/, a) ; the 

 peridium itself looks like a peripheral layer of similar spores, which however remain 

 united ; like the spores they contain red granules. The aecidiospores thus produced on 

 the leaves of Berberis develope a mycelium only when they germinate on the surface of 

 the blade or stem of one of the Gramineae, Triticum for instance or Secale. Then the 

 germ-tubes penetrate through the passage of the stomata into the parenchyma of the 

 plant, and the mycelium which they produce there forms uredospores (///, ur) in from 

 six to ten days on branches (basidia) which are crowded together more or less erect on 

 the cushion-like knots of mycelial filaments lying beneath the epidermis. The uredo- 

 spores too have the red granule?, and may be seen with the naked eye forming together 



FlG. 86. Pttccinia graminis. A germinating teleutospore t, the promycelium of which is forming the sporidia sf. 

 B a promycelium (after Tulasne). C a piece of the epidermis of the under surface of a leaf of Berberis -vnlgaris with a 

 germinating sporidium sp ; * its germ-tube which has penetrated the epidermis. D a germinating uredospore fourteen 

 hours after being sown in water. After De Bary, I.e. C, D magn. 390 times, A, B more highly magn. than C and D. 



long narrow red cushions on the leaves and spikelets of grasses. The uredospores are 

 scattered on the rupture of the epidermis and germinate in a few hours on the 

 surface of gramineous plants (Fig. 86, D), and on these plants only they develope new 

 mycelia, which again produce masses of uredospores in from six to ten days ; these spores 

 also send germ-tubes through the stomata into the interior of the host. While the 

 Fungus in its uredo-form thus produces many generations of plants in a summer on the 

 Gramineae, the formation of a new form of gonidium commences in the older clusters 

 of uredospores. By the side of the roundish unicellular uredospores appear long two- 



