of Laticiferous Tubes . 165 
Jacaratia sp. (Fig. 7). The structure of the leaf is some- 
what abnormal. The cells of the upper epidermis are large, 
and some invade the palisade-region. Amongst the normal 
palisade-cells are broader brownish cells which stain more 
deeply and contain more tannin. Most of the free parts of the 
tubes merely run from vascular bundle to vascular bundle. 
However, branches are sent up for a shorter or longer distance 
between the palisade-cells. 
Conduction of carbohydrates in Papayaceae . The leaves of 
the Papayaceae mentioned are not well suited for studying 
the possible function of the laticiferous tubes, because these 
latter have a relatively small free course. The leaves of 
Carica Papaya were full of starch. After they had been 
darkened for forty-eight hours the distribution of the starch was 
rather irregular. However, in certain regions of the leaf the 
starch was confined almost solely to the nerve-parenchyma. 
And seeing the direct connection of the palisade-cells with these 
nerve-parenchyma- cells, we cannot wonder that the laticiferous 
tubes show no signs of participating in the process of conduc- 
tion of starch. 
COMPOSITAE. 
In Hypochaeris radicata the disposition of the tubes of the 
leaf agreed with Haberlandt’s description, in that the tubes 
end in the mesophyll. The tubes frequently forked close to 
a mesophyll-cell, exactly as Haberlandt states. I failed to 
discover tubes ascending to the epidermis. 
Asclepiadeae. 
In the leaf of Asclepias curassavica the tubes, after leaving 
the vascular bundles, run loosely through the spongy paren- 
chyma and end there, or they end in the palisade-layers. A 
very few tubes reach the epidermis. Their loose and irregular 
course through the spongy parenchyma certainly does not 
suggest that the tubes are calculated to conduct plastic 
material by the shortest route. 
