CYLINDROSPORIUM ON STONE FRUITS 
It has been found that leaves which contain amygdalin produce 
also an enzyme, emulsin, which, under certain conditions, breaks the 
amygdalin down into benzoic aldehyde, hydrocyanic acid and glucose. 
Morse and Howard (20) found that wilted cherry leaves yielded 
much more prussic acid than fresh leaves, but offer no explanation 
as to why the leaves should do so. 
More recently H. E. and E. F. Armstrong (2), in an interesting 
paper on ''The origin of osmotic effects," find that prussic acid is set 
free in the leaves of the cherry laurel by treating the leaves with vapors 
of anaesthetics, with alcohols, or many other organic and inorganic 
compounds which enter the cells of the leaves. The authors think 
that when these substances enter the cells they change the osmotic 
relations in the cell, and enzymes are set free which break down the 
hydrolites stored there. 
Guignard (14), who has done much work on emulsin and cyano- 
genesis, found emulsin in the endodermis of the vascular bundles only 
in leaves of P. laurocerasus. He suggests that wilting, action of 
chemicals, anaesthesis, or anything which alters the osmotic relations 
of the cells would bring the emulsin and hydrolite together. 
Mann (19)^ states that, in curing certain grades of tea, leaves 
allowed to wilt slowly increase the amount of the enzymes which break 
down the objectionable compounds. He thinks that these enzymes 
are not present as such, but zymogens are present which break down 
and form enzymes when the leaves wilt. 
Green (13) thinks that in many of the plants enzyme antecedents 
exist first as zymogens, and in a few instances has shown rather 
definitely that such is the case. 
It is quite possible that the emulsin zymogen exists, along with 
amygdalin in the cells of cherry leaves, and that the enzyme is set 
free by slight changes in the osmotic pressure in the cell. Should this 
be the case certain observed phenomena (e. g., the rapid splitting of 
amygdalin in wilted leaves) could be more readily understocd. 
In whatever condition the enzyme exists, in cherry leaves it seems 
certain that it comes in contact with and breaks down the amygdalin 
when the leaf tissue wilts; and with this fact in mind a very plausible 
theory of "shot hole" formation can be formulated. When the 
acervuli and spores of Cylindrosporium break the leaf epidermis, the 
^Original paper not seen but only a summary in Fowler's "Bacteriological 
and Enzyme Chemistry." 
