34 TRANSLOCATION IN PLANTS 



upward moving, organic solutes, and particularly sugars, 

 are carried with the water in the xylem, it has also been 

 recognized that such movement to fruits may take place 

 through the phloem. Hanstein (1860) observed that if 

 phloem connections between fruits and the supplying leaves 

 are cut, fruit growth ceases. Strasburger (1891) made 

 similar observations but (p. 900) claimed the Umbelliferae 

 to be an exception. Curtis (1920a) demonstrated that 

 apple fruits ceased growth when the phloem connection 

 between the fruit and the leaves was severed, whereas if 

 there were leaves above the ring and these were either 

 below or above the fruit, there was appreciable growth. 

 Miinch (1930, pp. 183-208) reported more extensive 

 experiments than others on this phase of translocation. 

 He worked with apples, Quercus pedunculata, Castanea 

 vesca, Aesculus pavia, Sorbus aucuparia, Samhucus racemosa 

 and nigra, and Heracleum sphondilium. In all cases he 

 found, as had previous workers, that fruits whose phloem 

 connections with leaves were completely severed failed to 

 continue growth, whereas similar fruits connected by 

 phloem tissues with leaves either above or below the fruit 

 would continue growth. 



It is obvious to anyone who has observed the effects of 

 ringing on fruit development that the size of the fruits 

 that develop on ringed branches as compared with control 

 fruits, depends upon whether the rings are so placed as to 

 increase or decrease the total available supply of food 

 from the leaves. That is, if the ring is so placed that there 

 are many leaves on the same side of the ring as the fruit, 

 the latter will be large. If, on the other hand, the ring 

 isolates the fruit so that it is in phloem connection with 

 but few leaves, its growth will be shght. The behavior 

 of the fruit in this respect is very similar to that of the 

 cambium and diameter growth as observed by Knight as 

 early as 1801, and by Hales, in 1727. 



Miinch also reports experiments on the upward tranfer 

 of foods to fruits situated on defoliated branches. He 

 found httle or no reduction in growth of such fruits of 



