The Parasitism of Nectria cinnabarina. J. Line. 27 
itself directly in healthy tissues, but that it can do so after a 
period spent on a dead portion of the host. 
It is thought that the harmful action of the fungus is entirely 
due to its growth in the xylem elements, causing death of living 
cells above the infected area owing to water shortage. 
No evidence was obtained that it could ever enter a living 
cell until the cell was at any rate partially cut off from its water 
supply. No ill effects appear to be felt by the leaves and flowers 
on a stem, which may be almost completely blocked with 
Nectria at a lower level, until they suddenly show signs of 
wilting. It therefore would seem improbable that any toxic 
substance is secreted by the fungus which can affect living cells 
in advance of the fungal hyphae. Experiments are being con- 
ducted with a view to further elucidation of this point. 
It is commonly observed that the attacks of the fungus are 
much more frequent on red currant than on either black currant 
or gooseberry. The former, which is normally somewhat heavily 
pruned, furnishes a number of dead spurs each year, and these 
are observed to be the starting-points of the fungus in the great 
majority of cases. The time of the actual invasion of the main 
stem is not apparently related to the time at which the first 
infection took place. Observations show that the older bushes 
suffer more serious damage from the fungus than younger and 
more vigorous bushes of the same variety, but it is plain that 
the fungus has in most cases been growing for several years on 
the older bushes before actual death of branches on a large 
scale occurs. 
Very little information could be obtained as to the names of 
varieties in the orchards, although it was certain that differences 
in the extent of attack by the fungus under the same conditions 
did exist. Further work is being done in collecting evidence as 
to the different varieties, and the effect of soil conditions. 
SUMMARY. 
(1) The fungus was not found capable of effecting an entry 
into uninjured plant tissues. 
(2) It can occasionally establish itself when introduced into 
a wound in certain woody plants, more readily in the case of 
the lime and horse-chestnut than in the case of the red currant, 
but it usually failed to do so under the conditions of the experi- 
ments. 
(3) Its normal method of attacking the red currant is by 
spreading through the wood cells from a dead portion into the 
healthy wood. 
(4) Its harmful action in the first place is due to the stoppage 
