244 



Infection Experiments. 



Infection experiments were undertaken with a twofold 

 aim, in the flrst place, in order to see whether the fungus 

 which kills the branches is the same as that foimd on 

 fruits, and in the second place, to ascertain whether 

 healthy fruits can be attacked. 



In the flrst experiments a small pièce of the bark of 

 a trunk or branch was eut loose on three sides, so that 

 it could be lifted up like a lid. Under this were introduced 

 pièces of diseased tissue, taken from branches or fruits, 

 also spores from branches or pods or from mycélium 

 grown in pure culture. A bandage was placed round the 

 wound, which was kept moist. None of thèse infections 

 was successful, however. 



In a subséquent séries of experiments the tops ofvery 

 young branches were eut off and the planes of cutting 

 were infectcd. Thèse infections were likewise without 

 resuit. 



We obtained better results by cutting or tearing pièces 

 from branches having the thickness of a finger, infecting 

 the extremity and making round this a damp bandage, 

 or also by binding the extremity in a little bag of water- 

 proof paper, iiito which some water was poured, so tha'. 

 only the surrounding air rcmainod niojst. Of the ten 

 branches which we treated iii lliis maniicr, four were 

 attacked. Aftur a fuit)iiglit thèse branches were diseased 

 foi- a distance of y, — 1 mètre up to the place where they 

 jiijiied a thicker branch. Thèse thicker branches remained 

 unattacked. The control branches remained healthy. 

 Among the successful infections were three, in whirh the 

 infection-material was obtained from fruits. 



The DixdoOÀa, which causes rotting of the pods is 



