376 The Principles of Fruit-growing. 
a slight extent, by the mere mechanical action of 
the water. It is really remarkable that sand was 
such a perfect filter as to hold the great quantity 
of arsenic above a depth of three inches for over 
four months. If the soil in either experiment had 
been a homogenous subsoil, where the sun could not 
have cracked or checked it, it is fair to conclude 
that no arsenic could have penetrated it.”* 
Summary.—The fruit-grower may desire to have 
a very brief epitome of some of the cardinal sug- 
gestions touching spraying : 
1. Spraying is only one of several means or opera- 
tions which the pomologist must master if he aspires 
to the greatest and most uniform success. Other 
fundamentally important requisites are tilling, fertil- 
izing and pruning. 
2. Spraying is not necessary to successful results 
every year, but inasmuch as the farmer cannot fore- 
tell the need of the operation, he should spray as 
a matter of insurance. 
3. Spraying is almost sure to be of some benefit 
every year, particularly upon apple, pear, plum and 
quince trees, and upon grape vines. 
4. Spraying is of little consequence unless care- 
fully and honestly done. The spray must actually 
reach every point which it is intended to protect. 
5. Prepare for the year’s campaign during the 
previous winter, by reading the last teachings, and 
*For another discussion of this subject, and of the destination of copper 
in the soil, see Lodeman, “The Spraying of Plants,” 231-237. 
