46 LATICIFEROUS TISSUES OF PLANTS 



He also observed that in the green portions of the stem 

 communications between the vessels of the pith and cortex 

 occm" at the nodes. 



Arens has also noted the occurrence of laticiferous 

 vessels in the pith of Hevea trees. In a six-j^ear-old tree 

 which was 24 in. in girth at 3 ft. from the gromid, he 

 found from 13 to 20 laticiferous vessels in the pith. 



The cortex of mature Hevea trees contains numerous 

 laticiferous vessels which run in a longitudinal direction, 

 i.e. parallel to the axis of the plant, and form a complex 

 network by reason of their lateral communications. It 

 is these vessels which are of interest to the rubber planter, 

 and a general account of their development and distribu- 

 tion will be given in the next chapter. 



The natm-e of the laticiferous tissue in the seedlings of 

 Manihot Glaziovii, the Ceara rubber tree, was also in- 

 vestigated hy Scott * and afterwards by Miss Calvert 

 and L. Boodle. f These Avorkers found that this species 

 resembles Hevea hrasiliensis in having articulated latici- 

 ferous vessels which occur both in the cortex and the 

 pith of seedlings. The vessels in the cortex are connected 

 by numerous lateral passages, as in the case of Hevea. 



Little information is available regarding the latici- 

 ferous tissue of other rubber-yielding plants. It has 

 been stated already that the seedlings of Funtumia 

 elastica and Castilloa elastica contain non-articulated 

 laticiferous tubes formed by the growth of cells present 

 in the embryo, but no observations appear to have been 

 published as to the nature of the laticiferous tissue in 

 the cortex of the matiu-e trees. J 



Characters of Latex. — The latex is usually a white 

 fluid, almost indistinguishable from milk in appearance ; 

 sometimes, however, it is cream or yellow in colour and 

 occasionally pinkish or pale reddish-brown owing to 

 the presence of colouring matter in the bark. Like milk, 

 it is an emulsion, and consists essentially of a watery 

 fluid containing various substances in solution and holding 

 in suspension the minute globules of rubber substance. 

 These globules, which correspond to the fat globules of 



* Quarterly Jourruil of Microscopical Science, xxiv. pp. 194-204. 



t Antialu of Botany, i. pp. 55-G2. 



J For further information on this snViject 8ee, however, U Appareil 

 laticif^re dcs Caoutchoitticrs, by Dr. A. Mevmier (Iniprimerie Industrielle 

 et Financidre, 4, Ruo de Berlaimont, Bruxelles). 



