TRANSLOCATION OF CARBOHYDRATES 459 



remark that this objection was removed by the work of later 

 investigators who found starch in the sieve-tubes of numerous 

 plants. 



Of the many subsequent investigations carried out by the 

 method of ringing those of Lecomte (1889) may next be dealt 

 with. In the case of entire plants which were ringed in spring 

 after the expansion of the leaves he found that the vegetative 

 and floral growth above the ringing became much more active, 

 that callus developed more vigorously at the upper than at the 

 lower edge of the wound, and that the branches grew in diameter 

 considerably above the wound but scarcely at all below it. 



In order to study the last .phenomenon more closely 

 branches were ringed in June, and in September transverse 

 sections were cut two centimetres above and below the ringing. 

 The comparative development of tissues is shown in the 

 table below, which is taken from Lecomte's paper. (The 

 numbers represent divisions of an ocular micrometer.) 



From these examples it is seen that above the wound there 

 is a considerably greater development of tissues than below; 

 this applies especially to the phloem, that of Pniuus domestica 

 having above the wound three times the radial extent of 

 that below. In the cortex the difference is much less pro- 

 nounced and so Lecomte concluded that " the phloem above 

 the wound is richer than the cortex in nutritive substances 

 capable of being employed in growth." But as Pfeffer remarks, 

 in order for growth to occur the tendency to grow must exist 

 as well as a supply of materials; such a tendency is not very 

 marked in the cortex. 



In some other experiments the tissues were removed only 

 as far as the fibres outside the phloem. It was then found in 

 Sainbncus nigra, Cissies qidnqucfolia and the vine that the pads 

 of corky tissue formed on the two edges of the wound were 

 approximately equal and that there was no marked difference 



