REPORT OF THE STATE ENTOMOLOGIST I9QI2 85 
in considerable measure upon climatic conditions. The vigor of 
the roots and the lower portion of the trunk, which latter fre- 
quently escapes injury probably because of the thicker bark hin- 
dering penetration of vital tissues, is shown by the numerous 
sprouts on the lower part of badly affected trees. This new 
growth may be moderate in character or extremely vigorous, much 
depending upon the vitality of the tree and the number of sprouts 
developing. 
Miscible oils. An emulsion is defined as 
insoluble in one another, where one is suspended in the other in 
‘a mixture of liquids 
the form of minute globules.” There is no hint of a chemical 
change, the oil is simply more finely divided and, as a consequence, 
more evenly distributed through the preparation. It is still oil and 
possesses the properties of oil, as is readily seen on the disinte- 
gration of the familiar kerosene emulsion. The term “ miscible 
oil” has been employed in economic literature to designate emul- 
sions or preparations of oils, usually petroleum, mixing readily 
with water. A number of these have been placed on the market 
under various trade names. [Experience has demonstrated the 
utility of a general designation for this class of products. The 
commercial emulsions are usually more stable, that is, they dis- 
integrate less readily than the homemade kerosene emulsion. They 
contain oil in practically an unchanged condition so far as chemi- 
cal and physiological properties are concerned, and may be ex- 
pected to produce effects upon plants corresponding to the amount 
applied, other conditions being uniform. 
Injury by miscible oils. Many have been repeatedly assured 
that miscible oils, especially certain commercial preparations, can 
be applied to plants without injury. One manufacturer states 
that it is ‘absolutely impossible” for his product “to injure a 
tree where the simplest directions are followed.” Miscible oils can 
and have been used under conditions which would seem almost to 
preclude the possibility of injury. Nevertheless, we believe there 
is a risk in employing these materials, largely because of our ignor- 
ance of the physiological condition of the tree and the kind of 
weather which may follow the spraying, both of which appear to 
be important factors. In addition some varieties seem to be much 
more susceptible to injury of this character than others. Our ob- 
servations upon petroleum, noted above, appear to indicate much 
greater danger of penetration during the winter season, a time 
when the pressure of sap is greatly lessened. A sudden drop in. 
