DI-MORPHISM. 37 



Spliceria common to various plants ; tliese moulds 

 having been hitherto regarded as fungi perfect in 

 themselves. 



In the Uredines^ to which much of this volume 

 is devoted_, the genera known as Lecythea and 

 TricJiobasis are by some mycologists excluded 

 altogether^ as containing only species which are 

 mere forms of more highly-developed uredines_, 

 such as Fuccinia, Aregma, and others. On the 

 other hand^ they are retained by those who possess 

 a lingering doubt whether both forms may not be 

 distinctv, though developed from the same pustule. 

 As the two forms are distinct in appearance^ it will 

 better answer our present purpose to treat them 

 separately_, notwithstanding the belief that_, in a 

 scientific point of view^ the evidence is all in favour 

 of their union. 



In fungi of this kind the mycelium^ or delicate 

 root-like threads^ consists of thin filaments^ which 

 are spread through all parts of the plant occupied 

 by the parasite_, traversing the intercellular pas- 

 sages^ but rarely perforating and entering the cells. 

 This compacted and interwoven mycelium forms a 

 kind of cushion beneath each pustule^ on which the' 

 fruits of the parasite rest. By the increase of this 

 cushion and the swelling of the fruit_, the epidermis 

 which covers them is distended^ and ultimately 

 ruptured^ so that^ when ripened^ the spores escape. 

 It must be remembered that the fruit is of from 

 two to four kinds. Small bodies^ called spermatia, 



