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 pornologist 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. 



