142 PLANT LIFE. 



the septum below which it originated, the walls of branch 

 and hypha disappear at the point of contact, the result 

 being that the loop formed by the branch has opened a 

 communication between two cells of the hypha. It is 

 rather significant that clamp-connections are very charac- 

 teristic if not entirely confined to the large group of fungi 

 known as the Basidiomycetes, where every trace of the sexual 

 mode of reproduction has disappeared. 



The hyphse or mycelium forming the vegetative portion of 

 the fungus usually remain distinct; but in many species, 

 when conditions are unfavourable for active growth, or for 

 the development of the sporophore or reproductive portion 

 of the fungus, the vegetative hyphae becomes concentrated 

 into a solid mass called a sderotium. These sclerotia are 

 met with in widely separated orders of fungi, and, depending 

 on the species, vary in size from a mere point to spherical 

 or irregular masses six inches or more in diameter. When 

 dry, sclerotia become dry and woody in texture, and a 

 certain amount of differentiation is observable, the cells 

 becoming thick-walled and dark-coloured, forming a pro- 

 tective rind. These bodies may be looked upon as con- 

 centrations of reserve material, and often possess the power 

 of remaining dormant for a long period. Eventually, under 

 favourable conditions of temperature and moisture, they 

 produce sporophores, which as a rule are of a higher order 

 than the sporophores formed by the mycelium, previous to 

 the formation of sclerotia. Structurally sclerotia consist of 

 a mass of intricately interwoven, continuous or septate 

 hyphae, that become cemented together into a horny mass 

 when dry, due to the partial gellification of the outermost 

 portion of the cell-walls. 



A greater amoimt of differentiation is observable in the 



