10 



THE PARASITIC FUNGI. 



others, like Poiloxjilnn-fn I'mtui/nri, they take the form of broadened 

 i -l"s.-h -clinuinu hyphaf with haustoria. Frank describes a swell- 

 ing of tin- .".ei -iii-tube of Fmidadium trcmulae just before the 

 intectini; hypha pierces the cell-walls of its host. A similar 

 phenomenon ran be observed in Polystigma rubrum, in Gnomonia 

 I'l-i/tlin^tiiiiiii, and in the germinating aecidiospores of Mclampsora 

 (''/>/Tfiintft. Some other examples will be mentioned in our 

 next section. 



Haustoria of the epiphytic Parasites. 



The most inconspicuous haustoria are those of Herpotrichia 



and Trii'liuxjiiiiK-riii purnsitica, described by 11. Hartig. 1 



Kn:. -2. Haustoria of Trichosphueria parasitica. (Details on Fier. 88.) 

 (After K. Hartig.) 



They are tiny hyphal processes resting on the host-epidermis, 

 and sunk into the outer walls of the epidermal cells, so as to 

 pierce the cuticle but not the whole wall (Fig. 2, d, c ; also 

 Fig. 90). The Erysipheae are typical epiphytes, which weave 

 a mycelium over the surface of plants they attack ; the 

 mycelium retains its hold by adhesion-discs or appressoria, and 

 from certain parts of these a fine thread-like process is given 

 nlV, which, after piercing the epidermal wall of the host, swells 

 to a simple or branched sac, the haustorium. The 



1 /,. hrl.nrh </. lit,, i rn km nl:l,i ',<,, II. Anfl. English translation by Professor 

 Bomerville. Macmillan & Co., 1894. 



