INTRODUCTION TO CRYPTOGAMIC BOTANY. 



305 



vesicular spores, calling to remembrance those of Polycystis, 

 has been found by Corda on Peziza lahelluin, Bull. The 

 genus Nyctalis is so completely metamorphosed externally 

 by the stellate spores of Asterophora, that the true nature of 

 the matrix was long overlooked, and the gills or veins Avhich 

 form the hymenium, and which even in specimens infested 

 with the Asterophora produce perfect fruit, were supposed to 

 be mere representatives of an hymenium which was always 

 destitute of fructification. But, perhaps, one of the most 

 curious is a species which occurs, not imfrequently, in imported 

 Spanish Chesnuts (Fig. 69, a). The white substance of the 



Fi.or 69. 



a. Acrospeira mirahilis, Berk, and Broome, showiug the origin of the 

 spores, from the second joint of the spiral fertile threads. 



b. PapuIa>spora sepedonioides, Preuss, showing the young receptacle 

 above, and mature spore below. 



c. Ravenelia Indica, Berk. From specimens on Acacia, gathered in 

 Behar, by Dr. Hooker. 



d. Ravenelia glandidcBformis, Bei-k. and Curt. From S. Carolina, 

 on Desmodium. All magnified. 



two large cotyledons is comjDletely traversed and altered in 

 texture by the mycelium of the mould, while a few fertile 

 threads are produced in the free space between the cotyledons. 

 If a slice of the diseased cotyledon be placed on damp soil 

 under a bell glass, in two or three days the threads are beau- 

 tifully developed, and exhibit under the microscope a very 

 20 



