GEHr.IINATION AND GROWTH. 143 



comes at its apex a vital centre, and sprouts one or more linear 

 buds, of which the elongation is occasionally interrupted by the 

 formation of vesicular swellings. As Tulasne observes, the 

 pseudospores of the JEcidium and the greater number of Uredines 

 are easily wetted with water before arriving at maturity ; but 

 when they are ripe, on the contrary, they appear to be clothed 

 with a greasy matter which protects them from the liquid, 

 forcing them almost all to rest on the surface. 



The pseudospores of Jtoestelia are produced in strings or chap- 

 lets, as in JEcidium, with this difference, that instead of being 

 contiguous they are separated by narrow isthmuses. The ripe 

 pseudospores are enveloped in a thick tegument, of a dark brown 

 colour. They germinate readily on water, producing a filament 

 fifteen times as long as the diameter of the spore. This filament 

 is sometimes rolled or curved. Towards its extremity it exhibits 

 protuberances which resemble the rudiments of ramuli, or they 

 terminate in a vesicle which gives rise to a slender filament. 

 The tegument of these pseudospores, above all in those which 

 have germinated, and have consequently become more trans- 

 parent, it is easy to see has many pores, or round ostioles. 



In Peridermium the pseudospores, when dropped upon water, 

 germinate at any point of their surface. Sometimes two unequal 

 filaments issue from the same spore. After forty-eight hours 

 of vegetation in the air, the greater part had already emitted a 

 multitude of thick little branches, themselves either simple or 

 branched, giving to the filaments a peculiar aspect. Tulasne did 

 not on any occasion observe the formation of secondary spores. 



In the Uredines proper the germination seems to be some- 

 what similar, or at least not offering sufficient differences to 

 warrant special reference in Vredo, Trichobasis, Lecyihea, &c. 

 In Coleosporium there are two kinds of spores, one kind consist- 

 ing of pulverulent single cells, and the other of elongated sep- 

 tate cells, which break up into obovate joints. Soon after the 

 maturity of the pulverulent spores, each begins to emit a long 

 tube, which is habitually simple, and produces at its summit a 

 reproductive cellule, or reniform sporule. The orange protoplasm 

 passes along the colourless tubes to the terminal sporule at the 



