55 



3. Rale of increase of crops. 



In tte ease of crops it is obvious that we require to know only 

 the rate at which the volume of the crop iDcreases, and that 

 a knowledge of the rates at which the height of the crop and the 

 aggregate diameters and basal areas of the component stems in- 

 crease, is of interest only so far as these elements are so many 

 factors jn the growth of the crop, 



A. Determination of the increment at an; time. 



There are various methods of determining the rate at which a 

 crop has been augmenting in volume at any time. They are — 



I. By means op investigations in the crop itsblp. — In 

 determining' the increment it must never be forgotten 

 that no one class of stems can be taken as representative 

 of the whole crop, any more than any individual stem 



