GENERAL INFORMATION 19 



plants or seeds, for many spores are not attacked 

 by the digestive juices of the stomach and are thus 

 capable of germination under favourable conditions. 

 Birds carry diseased fruits from place to place. 

 Soil from an infected area may be carried by im- 

 plements, etc., to different parts of the same, or 

 other fields, e.g. spread of *'finger-and-toe " disease. 

 Diseases spread in this manner, i.e. carried by 

 animals, etc., although by no means easy to check, 

 can be more successfully prevented than those 

 whose spores are carried by the wind. 



How Fungi Gain Admission to the Plant. — It is 

 not definitely known how many parasitic fungi 

 gain entrance to the healthy plant, but it may be 

 in one of three ways : — 



1. Digestion of the cell wall. 



2. Through the breathing pores. 



3. At some wound. 



The delicate germ tube which protrudes on 

 germination is in some cases capable of gaining an 

 entrance to the plant by digesting the wall with 

 the ferments which it secretes. The germ tube of 

 Phytophthora, although usually entering at a breath- 

 ing pore, is also capable of digesting the cell wall, 

 while hyphze of Sclerotinia sclerotioruvi are capable 

 of piercing the cell walls of a variety of plants. 

 The number of funcri enterino- in this way is, how- 

 ever, probably over-estimated, for some minute 

 wound can often be detected. 



ry "SK 



