236 TRANSLOCATION IN PLANTS 



lessened diameter growth there. Fruits, if already present 

 above the ring and accompanied by many leaves, tend to 

 grow larger, sweeter, and brighter colored, and these 

 changes are usually explained as resulting from the higher 

 carbohydrate supply. The marked accumulations of car- 

 bohydrates above the ring, as demonstrated by qualitative 

 and quantitative tests, accompanied by a corresponding 

 deficiency below the ring, have been long recognized and 

 support the generally acceptable explanation that these 

 particular growth responses result from a disturbance in 

 carbohydrate transport brought about by the interruption 

 of backward flow by the ring. 



Other changes in behavior also result when a stem is 

 ringed. Elongation of shoots tends to be checked above 

 the ring and favored below the ring. Although these 

 changes in shoot growth are not usually explained on the 

 basis of altered solute distribution, the evidence is fairly 

 clear that a deficiency or at least relative deficiency of 

 solutes from the soil, particularly nitrogen, may account 

 for the decreased shoot growth above the ring and an 

 enhanced supply, either absolute or relative, of these same 

 solutes may account, at least in part, for the increased 

 shoot development below the ring. The reduced tendency 

 toward vegetative shoot growth above a ring is often 

 accompanied by an increased tendency toward the forma- 

 tion of flower primordia, and this is usually explained as 

 due to increased carbohydrate supply. 



It has long been recognized that ringing results in a 

 starvation of the roots and therefore a diminution of root 

 growth, as well as a cessation of storage in subterranean 

 organs and reduced growth of these organs. These 

 responses, also, obviously result from a disturbance in 

 normal transport of organic solutes. 



41. Relation between Solute Distribution and Regen- 

 eration. — When a stem is ringed, roots are Ukely to be 

 formed above the ring and shoots below. These perhaps 

 develop more commonly from dormant or suppressed 

 primordia, but in some cases they may be strictly adven- 



