264 REPORT OF THE HORTICULTURAL DEPARTMENT OF THE 
the contents of the cell sap, which coming in contact with the 
copper hydroxid adhering to the leaf surface causes more or less 
of it to pass into solution.” Bain* concludes as the result of an 
experiment that the secretions from peach Meee do not increase 
the toxic action of copper salts. He says: “ Both cane and grape 
sugar increase the action of the copper slightly, while gum arabic 
and the gum secreted by peach leaves are without influence on this 
injury.” 
*5Pons®* found that although acid and neutral salts of copper 
are strongly insoluble in fats and fatty matters, the hydrate and 
basic salts are rather easily soluble. -He believes the fatty 
matters of the cuticle of plants are comparable with animal fats 
and not with wax, and consequently that they would be likety 
to exercise a solvent action on copper salts. 
It should be said that we found in our work that the hairs 
of both the fruit and the leaf of the apple secrete a considerable 
quantity of some substance, whether “ fatty matter” or “ wax” 
was not ascertained. 
Whether the dissolved salts pass readily from cell to cell, 
and so cause the large blotches of russet, I do not know, but f 
think that they do not do so; for, Iam told by Dr. Van Slyke, 
Chemist of this Station, that dissolved copper salts upon coming 
in contact with the proteids in the protoplasm of the cell wou!d 
form an insoluble compound which would be stored up in the 
dead cells. If this be the case the copper poisoning does not 
spread from cell to cell. But, rather, the injured tissue lies, for 
most part, directly under the blotches of bordeaux mixture. 
Fruit injury seems to occur as follows: The part of an apple 
injured by copper poisoning is in the first stage thickly sprinkled 
with dead points —a circle of dead cells surrounding a stoma or 
a hair; in the enlargement of the surface which follows the 
growth of the young fruits the dead cells are unable to bear 
their share of the surface tension; the result is that the epider- 
mal cells are torn, the lacerations being of greater or less length 
and depth according to the fruit, the number of dead cells, 
rapidity of growth of the apple and possibly other factors. It 
is the dead cells, and the healing of these lacerations, the cicatri- 
zation of wounds, that causes the corky, russeted layer on fruits 
which we call bordeaux injury. 
“Bain (4, p. 54). 
* Quoted from Swingle (53, p. 21). 
Pons (47). 
