108 PHYCOMYCETES. 



originate from the whole mycelium or parts thereof, and are 

 isolated or united into a sorus. 



Synchytrium and Pycnochytrium.^ 



Here, as in Olpidium, the mycelial hyphae are wanting, and the 

 vegetative body escapes from the spore as a naked mass of 

 plasma, which is later enclosed in a membrane. This vegetative 

 body may also develop into a sorus of thin-walled sporangia: 

 these separate in water, and each ejects from a pore numerous 

 swarm-spores with a single long cilium. In the event of resting- 

 spores being formed, the membrane of the vegetative body 

 becomes thickened into a brown exospore. The resting-spores on 

 germination liberate their contents as a single mass, or as several 

 zoospores. In the former case the single mass divides at once 

 into zoospores, or into a sorus of sporangia, which ultimately 

 give off zoospores. 



These fungi are found in the interior of cells, especially of 

 the epidermis. The one cell inhabited by the fungus grows 

 out as a simple papilla, or several neighbouring cells are also 

 modified, and grow out along with the original one to form a 

 gall-like swelling. The species of Synchytrium generally in- 

 habit the epidermal cells of land plants, yet disease caused 

 by them is commoner in moist than in dry situations. They 

 cause so slight deformation and damage to cultivated plants that 

 they are of little practical importance. 



The Fycnochytrium of De Bary is regarded by Fischer as a 

 sub-genus, by Schroeter as a genus. 



Synchytrium. 



The sori of zoosporangia are formed by direct division of 

 the mature sporophore, and are enclosed in the colourless 

 membrane of the mother-cell. 



Synchjrtrium taxaxaci, De Bary and Wor. (U. S. America).- 

 This produces, especially on Taraxacum, warty galls composed of 

 a diseased epidermal cell, enlarged and surrounded by a wall of 



• Schroeter: Colin's Beitragez. Biol. d. Pflanzenl., 1875, and in EiigUr-Prantl 

 Pflanzenfamilien, 1892. 



De Bary and Woronin, Bericht. d. natforsch. Ges. zu Freiburg, 1863. 



2 We propose to indicate in this way species recorded in Seymour and Farlow's 

 "Host-index" for North America; British species by (Britain). (Edit.) 



