13 



the untoward influences that may surround them. One would 

 as soon think of deciding upon the stabih'ty of a house or 

 bridge by the number of chips that the builders have made. 

 Tannin. — Like crystals in vegetable tissues, tannin is con- 

 sidered as refuse matter, and not, with perhaps certain excep- 

 tions, further active in the vital processes of the plant. Tan- 

 nin, as recognized by salts of iron, is abundant in twigs, and in 

 transverse sections is found most common in the rind, and the 

 inner bark close upon the cambium, and between it and the 

 zone of bast. There is a great difference in the amounts of 

 tannin between the several species. The buds contain more 

 than the other portions, and in immature terminal buds the 

 tannin is quite generally diffused throughout all parts of the 

 soft tissue. 



COMPARISON OF VARIOUS SPECIES. 



The reader is now prepared to make a comparative study of 

 the food-materials in the terminal buds of some of our leading 



kinds of trees and shrubs, confining his attention for the pres- 

 ent to those with well-developed buds at the extremities of 

 the branches. In the horse-chestnut we have a typical illus- 

 tration of buds with large and therefore conspicuous parts. 



L 



A longitudinal section is made with great ease, and there is 

 noticeable absence of the grit found in many twigs. The 

 pith is very large, and at an inch or so below the bud it is 

 dry and filled with air. The starch deposit occupies a thimble 

 or nipple-shaped portion of the moist pith, above which is 

 the growing point with its proteid compounds. Instead of 

 growing for a long distance at the least expense and strength- 

 ening the upper portion by a deposit of lignin in the pith, the 

 wood zone continues of considerable thickness, and the buds 

 rest in this ring as a crayon is held by its handle or clamp. 



r 



Figure 4 illustrates these points better than can be described 

 in words. The small amount of starch present may be due to 

 the warm winter, for the varnish was much softened at the 

 time of gathering (February 20), and the moist (almost wet) 

 pith was filled with a mixture of the soluble carbohydrates and 

 the albuminoids ready for the initial growth. 



In remarkable contrast with the last arc the clusters of 



