15 



Plums have much more tapering twigs, and end In minute 

 terminal buds, but with considerable starcii located in a cone 

 of lignified pith, as has been mentioned for the apple and pear. 

 In the peach the terminal bud is large, but the starch is much 

 less abundant than in the pear and apple ; it is midway between 

 the pear and the cherry in respect to its starch-bearing, and 

 perhaps holds the same position as to the amount of mucilage 

 or gum. 



There are many species of trees that do not usually present 



any starch in the twigs of the last year's growth, among which 



are the various kinds of willows and poplars, but the older 



wood of the main branches, as a rule, contains more or less of 



this food substance. Among shrubs the elder and currant and 



gooseberry have but a small amount of starch in the vicinity 



of the terminal buds. In short, there seems to be no evident 



rule to guide one in the matter. Starch may be in abundance 



in one species w^hen least expected and almost absent from 

 another. 



OtJier Carbohydrates. — An explanation of the absence of 

 starch in many tw^igs is not far to seek. It may be due first to 

 the substitution for it of oil, as in many seeds as well as buds 

 and twigs. The pine family is a striking illustration of this, 

 in the buds and branches of the members of which a pitch 

 abounds, largely to the exclusion of starch. Sugars of the 

 various sorts in like manner may take the place of starch in 

 furnishing the carbohydrates needed for the growth of plants. 

 In the second place, starch may have been deposited, but 

 afterward changed into those closely related chemical com- 

 pounds that, being soluble in cell sap, arc ready for transporta- 

 tion and work. Rarely docs a mature bud not respond to the 

 Trommcr and Fehlin<7 tests, but those without starch in their 



vicinity indicate the largest amounts of the soluble starches, 

 as they are sometimes called. In this connection it may be 

 said that the wood of the common currant bush was thoroughly 

 examined because of a failure to find starch in the young 

 twigs. When the roots, however, were tested, it was found 

 that they abounded in starch- Albuminoids and sugars were 

 present in the ends of the twigs, while the storehouse of starch 

 was below ground. 



