i8 



All of the ba^e of the bud c is charged with albuminoids 

 and carbohydrates that do not respond to the starch test. 

 When the wood, d, of the twig is reached, it is found filled 

 with starch, as indicated by the shading. Near the base of the 

 pistil, or miniature peach, is a triangle of starch-bearing 

 tissue. Occasionally, starch is also found in the pistil and the 

 stamen-filaments. These last need to undergo rapid growth 

 at time of blossoming. Whether this starch was stored in 

 these parts, far away from the great reservoir of this material, 

 during the growing season, or has been laid down afterward, 

 IS a question that is not answered. It is, however, a well-known 

 fact, that starch can be deposited, then dissolved, and re- 

 deposited in another place repeatedly within a short time 

 when such a chancre of the carbohydrates is of advantacre to 

 the plant. A study of the formation of the callus, and of the 

 knitting tissues of grafts, is interesting in this respect. It is, 



4- 



however, true, that when the flowers develop the reservoir at 

 the base of the peach pistil becomes emptied of starch, and 

 the tissue, not being thick-walled like ordinary starch-bearing 

 cells, is similar to that around it. 



TRANSVERSE AND LONGITUDINAL SEC- 

 TIONS OF TWIGS. 



An ordinary twig of the last season's growth consists o( 

 the following parts : (i) A central cylinder of pith which runs 

 the whole length, ending at the tip in the terminal bud. This 

 pith consists of many-sided cells, which are about as long 

 as broad, and packed so closely together as to leave but 

 few cavities, called intercellular spaces, between them. The 

 cells nearest the center are usually largest, and the outermost 

 smallest, and have the thickest walls. (2) Next outside of 

 the pith is a ring or zone of wood, which is very thin at the 

 upper end of the twig, but gradually becomes thicker as the 

 basal end is approached. This wood consists of long ducts 

 or vessels running longitudinally in the twig, and surrounded 

 by slender, thick-walled flexible wood cells. The wood is the 

 most substantial part of a twig, and makes up the greater 

 part of any tree. In the wood ring of the twic: ^^^ thin 



i 



plates of pith-like cells, which reach from the pith to a thin 



