DT-MORPHISM. 35 



tliemselves perfect plant s_, but merely conditions of 

 other fungi of a Mglier order^ little differing it is 

 true in external appearance to the naked eye^ but 

 offering material differences in structure under the 

 microscope. Upon the white mould-like threads^ 

 spherical bodies are produced in the autumn^ con- 

 taining little sacs or asci filled with spores ; and in 

 this condition the plants are arranged under the 

 genus Erysiphe, whilst the species of Oidium which 

 represented their imperfect condition_, are excluded 

 from the system. Here^ again^ we have examples 

 of di-morphism. 



In the Journal of the Microscopical Society, Mr. 

 F. Currey has detailed several instances of di- 

 morphism which have fallen within his experience. 

 In one instance he has shown that a small simple 

 spored fungus, termed Cryptosporium Neesii, Ca., 

 is only a state or condition of a fungus with com- 

 pound fruit, belonging to the Sphoeria section of 

 ascigerous fungi, called Valsa siiffiisa, Fr. Both 

 plants are exactly alike externally, but the peri- 

 thecium, or flask-like receptacle containing the 

 fructification, in one instance only holds naked 

 spores, and in the other the spores are contained in 

 little elongated vesicular bags or asci, which are 

 packed within the perithecium. 



Whilst writing this, one of the most wonderful 

 books in a book-producing age lies beside us; it 

 is the second volume of a work on fungi, by the 

 brothers Tulasne ; and this, as well as its prede- 



D 2 



