THE MUSHROOM TRIBE. 287 



stalk underneath the cap, and concealing the spores 

 within their folds. When the Mushroom has gained 

 its full size, its stalk is surrounded at the base by a 

 thick fleshy sheath, called the volva, or wrapper; 

 from what you have seen of its gradual progress, 

 you will have observed that the wrapper is nothing 

 but the remains of the skin within which the fungus 

 was formed. I send you a copy of a beautiful illus- 

 tration of these phenomena by Professor Th. Nees 

 V. Esenbeck, of Bonn, by whom they were observed. 



So simple is the growth of this and such plants, 

 and so remarkable are the circumstances under which 

 they are formed, as to have given rise to the belief 

 that they are not propagated by the agency of spores, 

 which are always sure to reproduce the plant from 

 which they originate, but are dependent for their 

 peculiar appearances upon the different circumstances 

 under which they are developed. Professor Nees v. 

 Esenbeck has proved that whatever error there may 

 be in such opinions generally, they are at least well 

 founded in the case of the Veiled Mushroom ; for 

 he ascertained, by careful observation, that the same 

 cobwebby matter which gave birth in hothouses to 

 the Mushroom, in long and bright days when there 

 is plenty of light, produced nothing but a plant called 

 Sclerotium Mycetospora, in the autumn, winter, and 

 spring, when the hothouses abounded with heat and 

 moisture, but when the days were short, the sky 

 cloudy, and light deficient. 



The last and lowest of all the tribes of plants are 

 the Sea-weeds and their allies ; these productions 



