226 VEGETABLE PHYSIOLOGY 
To a certain extent the cortex of the plant shares the 
translocatory function. The contents of its cells include a 
certain amount of carbohydrate material, but their reaction 
is distinctly acid, so that this region is probably concerned 
much more definitely with the transport of vegetable acids, 
so far as it takes part in translocation at all. At the same 
time it is impossible to localise the transport of food 
exclusively in the bast. 
Other parenchymatous tissues are sometimes the region 
of transport. In many germinating seeds there is a trans- 
ference of large quantities of nutritive substance across the 
endosperm to the embryo, and in young seedlings similar 
transport takes place through pith as well as cortex. 
The vessels of the wood, which we have seen are the paths 
of the transpiration current are probably not concerned 
normally in the translocation of manufactured products, 
though exceptionally they may contain certain amounts 
of proteins, amido-acids, &c., in solution. Their function 
in this respect is, however, unimportant, and the presence 
of such bodies in them is mainly accidental. 
An important exception is seen in the resumption of the 
growth of a tree in the spring. Before the unfolding of its 
leaves enables photosynthesis to commence, a stream of food 
from the winter reservoirs takes place which travels upwards 
in the wood. 
It is doubtful how far the laticiferous systems, which 
are present in many plants, may be regarded as channels 
for translocation. No doubt latex contains many nutritive 
products, both nitrogenous and non-nitrogenous, but there 
is reason to think they are to be referred to the storage 
rather than to the transporting system. 
