12 FUNGOID DISEASES 



sinks into insignificance under the profuse produc- 

 tion of spores. 



Pa^^asites^ and Saprophytes. — According to the 

 source of food, we divided fungi into parasites and 

 saprophytes (see page 2). This division, how- 

 ever, is somewhat arbitrary, for many parasitic 

 fungi are capable of living wholly or partly as 

 saprophytes. In like manner, some saprophytes 

 are able to exist as parasites. A better division is 

 as follows : — 



1. Totally Parasitic. — Fungi whose whole life is 

 spent on living matter, and which, so far as our 

 present methods of cultivation allow, will not grow 

 on dead organic substances, e.g. the Ui^edinales 

 (rusts) and the different species of Eiysiphacece 

 (mildews). 



2. Semi-parasitic, — Fungi which are capable of 

 growth for all, or part, of their life cycle as sapro- 

 phytes, but which are typically found parasitic for 

 part, or all, of this cycle. The smuts are capable 

 of growth indefinitely as saprophytes, but do not 

 produce the typical smut spores unless they grow 

 as parasites ; on the other hand all stages of the 

 potato fungus [Pkytopht/iora) can be grown sapro- 

 phytically, although in nature it is commonly found 

 only as a parasite. 



1 A parasite may be looked upon as a robber of the plant, and 

 stands in much the same relation to the host as a lazy fellow does 

 to his victim, from whom he obtains food and money. 



