MODE OF LIFE OF THE PARASITIC FUNGI. 13 



haustorium on an endophytic mycelium is that exhibited by 

 the parasite Cystoiyus ; the hyphae send oft' very fine filaments 

 which penetrate the walls of a host-cell and swell up to little 

 button-like sacs. Many Peronosporeae (P. irygmaca, P. nivca, 

 P. viticola and Phytophthora omnirora) have haustoria of the 

 form just described, whereas others have them thread-like and 

 branched (P. ealofhcca of the woodruff), or crenately lobed (P. 

 parasitica). 



Amongst the species of Uredineae and Ustilagineae, haustoria 

 are not uncommon and present many varied forms. They are, 

 however, few in number, or confined to certain parts of the 

 mycelium, so that they may be easily overlooked. 



Haustoria in the form of long sacs of various lengths are 

 produced by Melampsora Goeppcrtiana in the tissues of both 

 cowberry and fir-needle. Gymnosjwrangmm in juniper has 

 occasionally very delicate button-like haustoria. Endophyllv.m 

 sempcrvivi in the house-leek has haustorial branches which, 

 according to Zopf, are coiled together and anastomose frequently 

 with each other. Ttthurcinia amongst the Ustilagineae possesses 

 short branched haustoria resembling one-sided clusters, and 

 Melanotacnium endoycnum has similar' haustorial-tufts even more 

 branched.^ Urocystis pompholygodcs in Hcpatica triloba has spirally 

 coiled haustorial hyphae, while TiUctia endopliylla, Sorosporium 

 saponariae,^ and many species of Ustilayo, have haustoria \vith 

 the form of knotted hyphae. 



Amongst the Hymenomycetes, EwhasitUum vaccinii forms 

 a mycelium which permeates the host-tissues with numerous 

 hyphae, but the only haustoria are hyphae which here and 

 there penetrate into a cell. No haustoria have as yet 

 been found amongst the Basidiomycetes,^ Pyrenomycetes, or 

 Discomycetes. The two groups last-mentioned have an inter- 

 cellular or intracellular mycelium, which as a rule quickly 

 kills all cells with which it conies in contact. 



^ SenckenbercjiHche vadtr/orsch. Ge.s. Ahhandl. 1880. Plates I. and IV. 



-Primjsheivis Jahrbiich, 1869. Plates VII., VIII. 



*Sarauw has figured haustoria in mycorhiza of beech, without however 

 determining exactly whether they belonged to a Hymenomycete. Reess also 

 figures similar organs on mycorhiza produced liy one of the Tuberaceae. 



