CHYTRIDIINEAE 55 



that was repeated in regard to Protozoa as hosts, and was 

 corrected by Dangeard in 1894, as -is explained below. 



One group, the Synchytriaceae, differs so widely from 

 average fungi and approaches the Sporozoa so closely in 

 constitution and life-history that errors are likely to have 

 been made. Most Synchytrians do not appear to inflict on 

 their hosts more than local damage, but Synchytrium 

 endiobioticum, by attacking certain kinds of potato 

 threatened to destroy the crop over large areas of England. 

 The parasite causes tumours which resemble cancer more 

 nearly than does any other tumour of plants. 



In other Chapters of this book I give reasons for my 

 belief that the parasites which cause cancer, sarcoma, 

 syphilis, smallpox, and other diseases in man and animals 

 are allied to the genus Synchytrium. 



Wide differences are found between forms at the extremes 

 of the Chytridiineae, and, though linking species exist, it 

 has been doubted whether the grouping represents a natural 

 affinity, that is a common descent, or merely a likeness of 

 form caused in organisms of varied descent by their living 

 under like conditions. De Bary recognised four main groups, 

 now made into as many orders : Rhizidiaceae, Cladochytri- 

 diaceae, Olpidiaceae, and Synchytriaceae. 



The two former have a mycelium, and hence are grouped 

 as Mycochytridiinae ; the two latter without mycelium, 

 hence Myxochytridiinae. 



The mycelial forms may be akin to the genus Ancylistes, 



