TRANSLOCATION OF CARBOHYDRATES 467 



p. 358) he considered that " in the case of a very vigorous 

 transport of starch , . . even the phloem of the vascular bundles 

 may take part in it." 



With regard to the laticiferous tubes Sachs was inclined 

 to think that the presence of carbohydrates in their contents 

 could only indicate that the tubes served to convey these 

 substances to the growing points. 



A considerable amount of work has been done upon the 

 function of latex by observing the changes in its constitution 

 during different stages of the growth of the plant either under 

 normal or artificial conditions. 



For example Faivre (1866) found that the latex of Moras 

 alba in vigorously growing parts of the plant in spring is 

 very thin and apparently poor in contained substances ; from 

 this he concluded that it plays an important part in vegetable 

 nutrition. 



Schwendener, who repeated the observations in 1885, could 

 come to no definite conclusion. He found, however, that " in 

 those organs whose latex had become thin there occurred now 

 and then plug-like masses which had evidently arisen from 

 clotting." These were composed of numerous little spheres 

 closely packed together. Schwendener felt he could not give 

 any opinion upon the quantity of materials used in this way 

 but at all events the fact is one to be kept in mind when dealing 

 with changes in the fluidity of latex. 



In referring to this point Kniep suggests that in plants 

 whose tissues undergo changes in preparation for a winter 

 rest, it would not be very surprising if changes also occur in 

 the latex which result in its becoming thicker and more slimy. 

 He also suggests that the thinning observed in the spring may 

 be due in part to the water forced into the tissues at that time 

 of the year. Moreover Faivre did not demonstrate an actual 

 increase in the contained substances on the approach of winter, 

 which Kniep thinks would be necessary in order to prove that 

 the latex constitutes a reserve. 



Faivre also grew seedlings of Tragopogon porrifolius in the 

 dark and again found that the latex became more watery. 

 Similar results were obtained when plants were grown in light 

 but in an atmosphere devoid of carbon dioxide. He concluded 

 from such results that latex is produced in the leaves and is 

 translocated to places of consumption, as apparently it loses 



