342 APPLICATION OF PRINCIPLES. 



seasons of the year. When a top-dressing is applied 

 in the spring, the lawn profits by it so long as it con- 

 tinues to grow vigorously ; but the quick approach 

 of summer daily interferes with the force of this kind 

 of vegetation, and diminishes the effects of the 

 manure. On the contrary, if October is the season 

 chosen for the operation, the grasses are then begin- 

 ning to grow steadily, the operations of the mower 

 are, or should be, suspended, and there are seven clear 

 months at least during which the effects of the 

 manure continue to be felt. 



It may be indifferent at what season such manure 

 as bones, and other kinds of matter which decompose 

 very slowly, are employed; yet there can be no 

 doubt that upon every known principle they also 

 should be given at a time when vegetation is most 

 active; hence the every-day practice of digging 

 manure into the borders of a garden in spring, or 

 shortly before an annual crop is about to be commit- 

 ted to the soil. 



As to the manner of applying manure, it must be 

 obvious that it can be of no use unless it is in contact 

 with the absorbing parts of the roots; now those 

 parts are the young fibres and spongioles, as has been 

 already stated (23, 24), and, when plants have arrived 

 at any considerable size, the roots form the radii of 

 a circle whose circumference is the principal line of 

 absorption. This being so, if a plant has arrived at 

 the state of a bush or tree, it is useless to apply 

 manure at the base of the stem, because that is pre- 

 cisely where the power of absorption is the weakest, 



