1 26 Salmon* — Further Cultural Experiments with 
In one experiment in which a leaf was pricked with a pin, a slight 
susceptibility 1 was induced. The susceptibility was restricted to the cells 
at the edge of the holes caused by the pin. 
In further experiments an injury to the leaf was caused by stamping 
out with a cork-borer a circular piece of the leaf-tissue 4 mm. in diameter. 
Conidia sown on the cells at the edge of the hole were able to cause good 
infection, and produced eventually little patches of mycelium bearing some 
hundreds of conidiophores. Ascospores, also, sown at the same place, 
proved able to cause infection. 
Experiments were then made with leaves which had been injured by 
having large pieces eaten out of them by slugs. Conidia and ascospores 
were sown over the surface of such injured leaves, and proved able to infect 
the cells at the edge of the bitten places, producing on these cells little 
patches of mycelium bearing conidiophores, while elsewhere on the leaf 
they were not able to cause infection. 
In a large number of experiments leaves were injured by pressure in 
such a way that patches of bruised cells were produced. In some cases 
the end of a vertical wooden rod (with a flat surface, 7 mm. across) was 
placed on a leaf laid on a glass slide, and a pressure exerted for a certain 
time by means of a weight attached to the rod. Bruises were made, also, 
by pressing hard, with the hand, the rounded end of a glass rod on the leaf 
placed on a glass slide ; and also by nipping the leaf hard at the margin 
with a pair of forceps. In all the methods the bruised cells themselves 
(unless they were killed), proved susceptible, and also the cells immediately 
surrounding them. 
The effect of injury caused by the action of narcotics was then tried. 
An exposure to ether vapour for i| or 2 minutes was found to 
render the leaf susceptible. In some cases the susceptibility induced 
was very marked, the leaf presenting, a few days after inoculation, 
the appearance of being almost fully infected over the whole of the 
inoculated area. 
Exposure to chloroform vapour for 10 seconds, also, induced some 
degree of susceptibility. 
Immersion in a mixture of alcohol and water, and also exposure to 
vapour of alcohol, rendered leaves in many cases remarkably susceptible. 
Leaves immersed for 2-22 hours in a io°/ 9 mixture of alcohol and water 
were rendered, in several instances, susceptible to such a degree that the 
conidia sown produced over the inoculated area abundant patches of mycelium 
bearing many hundreds of conidiophores. The same marked susceptibility 
was induced in leaves exposed for 3 minutes to vapour of alcohol. 
The effect of injury by heat was then tried. Leaves were placed in 
1 i. e. to the attacks of a ‘ biologic form ’ which is unable to infect uninjured leaves of 
the species. 
