i8 - 



sufficient to draw attention to the following facts observed by 

 myself : if young trees are examined, one to three years old, it 

 will be found that the interior of the stem contains pith consisting 

 of thin-walled cells. Fibres of bast are completely wanting in 

 the pith. Some isolated, inter-communicating laticiferous vessels 

 run through the periphery of the pith.^ The pith, rich in starch, 

 is surrounded by dense wood. The living cells of the wood 

 are so rich in starch, tha(t a solution of iodine in diluted 

 alcohol will colour the whole body of wood an intensely dark blue. 

 On the outer surface of the wood, the creative tissue, the cambium, 

 is found, through the activity of which the tree grows in girth. 

 By division, it forms cells towards the interior, that enlarge the 

 wooden ring, and others towards the exterior, that thicken the 

 bast. Outside the cambium the bast is situated. In this a number 

 of laticiferous vessels are diffused, which like those in the pith, are 

 parallel to the axis of the tree and united by numerous cross- 

 connections. They, as well as the other cellular tissues of the bast, 

 are continuously reproduced by the cambium. Outside the bast, 

 last of all is the cortex. In it as well isolated laticiferous vessels 

 occur. The greatest amount of latex, however, is contained in 

 the laticiferous vessels, which are situated in the parts of the 

 bast, that adjoin the wood, and are still young. If we examine the 

 young green twigs of these trees, in which lignification has not 

 yet begun, we perceive that the medullary and cortical laticiferous 

 tissues, as well as those of the bast, are here and there united by 

 cross-connections, especially in all those places where a leaf or a 

 side branch emerges, namely at the nodes. But these connections 

 are not found in those branches, in which an unbroken ring of 

 wood surrounds the pith. 



Older trees, which are what we have to consider for tapping, 

 do not differ much anatomically from younger ones. However, 

 I have made one significant observation, namely, that medullary 

 laticiferous vessels seem to have lost all importance, and have 

 become quite valueless in older trees. Their walls are of a 

 brownish colour, so are their contents; in many cases the vessels 

 have been compressed by the adjoining pith-cells. Naturally all 



4 Miss A. Calvert has already described correctly the distribution 

 of laticiferous vessels in -the stem of Hevea trees. Vide her short treatise: 

 "The laticiferous tissue in the stem of Hevea Brasiliensis. Annals of Botany." 

 Vol. I. 1887-88. Page 75. 



