TRANSLOCATION OF CARBOHYDRATES 465 



Two years later, in 1866, Faivre expressed his belief that 

 latex is really a nutritive sap, an opinion partly based upon 

 an experiment with a small plant bearing eight leaves of a 

 species of Ficus, At a point a few centimetres above the in- 

 sertion of the roots he cut away a ring of tissue in the usual 

 manner. After two years instead of the original eight leaves 

 above the ringing there were twenty-five. Below the ringing 

 no leaves had developed, the cortex had shrivelled and the 

 roots showed no increase. But as Kniep pointed out, this 

 experiment does not show that the latex has a nutritive value. 

 A similar result would have been given by a plant without 

 latex, for the assimilates formed by the initial eight leaves 

 could well be employed in the production of new tissues. 



In order to do away with this objection Kniep worked 

 with Ficus Carica in a somewhat different manner. In. May, 

 before the plant had developed leaves, he made ringings on 

 several shoots at various distances from their terminal buds, 

 and watched the subsequent development of the leaves and 

 the increase in length of the newly-formed internodes. To 

 minimise as much as possible the formation of assimilates 

 above the ringing the young leaves were removed very shortly 

 after they had unfolded ; in a similar manner the young leaves 

 of unringed twigs were removed. It was found that in equal 

 times the leaves at the end of the unringed twigs grew to a 

 much larger size than those on the ringed twigs. The for- 

 mation of new leaves on the ringed twigs became continually 

 weaker, until at last it quite ceased ; this occurred so much 

 the sooner the nearer the ringing had been made to the 

 growing point. 



From these experiments, and from others carried out with 

 plants grown for a time in darkness, Kniep concluded that in 

 a ringed twig development of the upper portion is only possible 

 at the expense of the reserves already stored in its tissues 

 and that the medullary laticiferous tubes contribute little if 

 anything to the formation of new tissues. 



It may be noted that the greater development of adventitious 

 buds upon the lower portions of ringed shoots than upon the 

 corresponding portions of unringed shoots, repeatedly observed 

 in these experiments, suggests that an upward conduction of 

 formative materials in the tissues removed by the ringing was 

 prevented, the result being that more nutriment became available 



