DI-MOEPHISM. 43 



stylospore and exposed portion of its tube, then 

 separates itself from those parts, which become 

 dispersed. The active part increases and ramifies, 

 and produces a mycelium which spreads through 

 the intercellular passages of the parenchyma. At 

 the end of from six to eight days, the whitish spots 

 appear on the surface of the fosteriag plant, and 

 indicate that the fructification of the parasite is 

 about to commence. The epidermis is elevated 

 and broken, and little brown pustules appear 

 through the openings. These arc the stylospores 

 of Uredo, which are produced ia immense quan- 

 tities, and soon cover the pustules with a deep 

 brown dust. Later, the formation of the stylo- 

 spores is arrested, and the true germinating spores 

 appear in the same pustules. 



The stylospores of Uredo are borne singly at the 

 top of short filaments. On arriviag at maturity 

 they detach themselves. They are of a globular 

 form, with a reddish brown epispore, provided with 

 little pointed prominences, and three pores at equal 

 distances. After maturity they germinate ia pre- 

 cisely the same manner as the stylospores of the 

 cluster-cups. They enter only through the stomata 

 of the epidermis. The pulvinules are identical with 

 those which the stylospores .of JEcidium originate, 

 and they also produce true spores at the end of 

 their vegetation. No other fruit arises from them. 

 These organs, therefore, always reproduce the same 

 form to which they owe their origin. 



