232 THE " SHOT-HOLE " FUNGI OF STONE-FRUIT TREES. 



excretes a ferment or poison, causing the death of any cell it mny 

 reach, and consequently the effects are so deadly and so circum- 

 scribed that the well-known appearance is produced. Duggar, on 

 the other hand, is of opinion that it is not due to any peculiarity 

 on the part of the fungi, but to some inherent property of the 

 plant itself, wherebj^^ it has this peculiar reaction to injuries 

 received. He called attention to the fact that nearly all injuries 

 of stone-fruit trees take the form of shot-hole effects, but the 

 fungi concerned in these effects were only studied to a slight 

 extent. 



My own observations generally agree with the latter, and show 

 that the healing tissue is onty formed round the spot while the 

 leaf is alive, and that it is a protective check against injuries 

 produced by fungi and other agents. 



While PJi'ijllosticta prunicola and P. pefsicce have been found 

 on the '' shot-hole" of Apricot-leaves from South Australia, no 

 species agreeing with P. circumscissa of Cooke has been deter- 

 mined. It might either be an immature form, or very probably 

 P. persicce determined by Saccardo in 1879 on Peach-leaves. 



