CHYTRIDIUM 91 



CHYTRIDIUM (A. BRAUN) 



Zoosporangia sessile in cells of the host-plant, the base 

 forming a root-like continuation cut off from the sporangium 

 by a septum, zoospores globose, i-ciliate. Hard- walled 

 resting-spores are formed in the tissues of the host. 



Chytridiosis of the vine. A somewhat startling account is 

 given by Prunet, respecting the occurrence of a species of 

 Chytridium which he has found as a parasite on the vine. The 

 fungus is stated to be present on all the organs of the plant, 

 and also in all the tissues. It is frequently so abundant that 

 each of the living cells included in a section contains one 

 sporangium, very frequently two, rarely three or four. This is 

 especially true of the cells of the pith, especially when their 

 presence is made clear by staining. 



According to the special organ, or the special kind of 

 tissue, the Chytridium produces very different effects, is the 

 real cause of a number of ill-defined diseases, as ' d'anthrac- 

 nose ponctuee, anthracnose deformante, gommose bacillaire, 

 gelivure, roucet, brunissure, brunissure-rougeole, maladie 

 pectique, maladie du coup de pouce.' It is also said to be the 

 cause of certain kinds of chlorisis, and of various ailments of 

 the vegetative and reproductive organs, which the author 

 promises to enumerate in the future. It has also been proved 

 to be the cause of the disease called mal nero attacking 

 vines in Italy. 



The fungus proved to be a new species, and received the 

 name of Chytridium viticolum (Prunet). 



Zoosporangia ovoid or fusiform, terminal or intercalary, 

 10-40 x 3 15 p. Zoospores globose, with one delicate cilium, 

 i '5-2*5 p diam. 



Some of these sporangia are produced in pairs, of which 

 one is smaller than the other, and shrinks as * if its contents 

 had passed into the larger one, suggesting fertilisation.' The 

 zoosporangia constantly give off fine filaments of mycelium, 

 which pass into adjoining cells and form zoosporangia, which 

 again repeat the same process. The zoospores soon germinate 

 and give off germ-tubes, which spread in the tissue. Cysts or 

 thick- walled resting spores are formed, which after a period of 

 rest give origin to zoospores. 



Up to the present, so far as I am aware, this dreadful pest 



