GENERAL INFORMATION 13 



3. Totally Saprophytic. — Fungi which are un- 

 able to exist as parasites, and which in consequence 

 do not cause disease to either plants or animals. 

 They merely play the part of scavengers, hastening 

 the decay of refuse matter. 



4. Hemi- saprophytic. — Fungi which live chiefly 

 as saprophytes, but which are able to exist either 

 partly or totally as parasites, e.g. various species of 

 Mzccor and Penicillium ; or even more so the dif- 

 ferent species of Polyporus — seen as sponge-like 

 masses on trees — which, as parasites, are able to 

 kill living cells, but are also capable of living totally 

 saprophytic. 



Each of these four heads might be sub-divided, 

 but for this work it will suffice to divide the purely 

 parasitic fungi into : — 



(a) Epiphytic — parasites which live on the surface 

 of the host, e.g. species of EjysiphacecE (mildews). 



(^) Endophytic — parasites which live inside the 

 plants ; either in the intercellular spaces (the space 

 between the cells) or inside the cells, e.g. Phyto- 

 phthora infestans inside the cells of the diseased 

 potato. 



Effect of Parasite on the Plant. — The changes 

 brought about by parasitic fungi are exceedingly 

 varied ; the plant may succumb to the attack of the 

 fungus in a few days, e.g. as seen in the "damping 

 off " of cress, or the host and parasite may live to- 

 gether for a long time without disastrous results, 



