336 
Notes. 
say that the blind endings of the laticiferous system are generally 
connected with the palisade-cells. 
If it is improbable that a plant would build up so elaborate a system 
for the storage of waste products, it is possible that this method of 
terminating among cells in which assimilation is carried on may 
point to a storage or means of transit of reserve products. 
This is further borne out by the extremely early appearance of the 
system in the leaf. A longitudinal section through a stem-apex of 
Euphorbia pulcherrima , for example, shows, in leaves just beginning 
to unfold, a well-developed system with its earliest branches extending 
to the palisade-layer. 
Again, if latex is simply waste material, old leaves should contain 
large quantities of it, but this is by no means the case. 
If young leaves and old leaves are lightly punctured, the young 
leaves exude far more latex than the old ones, and the same is true 
for young and old shoots. 
Micro-chemical tests give the same results. If starch is present in 
the latex, a section of a young leaf shows the tubes well stored with it ; 
while in an old or a fallen leaf it is difficult to find a trace, even if the 
iodine-method of staining is used. The starch has evidently been 
handed on from the laticiferous system to other parts of the plant. 
Testing for proteids with Millons’ reagent, or by the xanthoproteic 
reaction, gives completely parallel results. Ficus Carica is a possible 
exception, for here one occasionally finds granular masses in the tubes 
which give proteid reactions. 
Though caoutchouc may be met with in fallen leaves, yet, from 
what is known of its chemistry, it is hardly likely that this substance 
has any nutrient value in the plant ; but there is a possibility that, as 
do many other terpenes, it may absorb oxygen as ozone. When the 
endings of the tubes, and Schunck and Brebner’s 1 demonstration of 
the presence of ozone in the palisade-layer, are taken into consideration, 
this view becomes more tenable. Direct proof of this has not been 
obtained, though testing latex with Wurster’s papers and with mercury 
points to the presence of minute quantities of free ozone. I hope to 
obtain evidence upon this point, among others, while examining the 
india-rubber industry in East Africa. 
To determine whether any physiological connexion exists between 
1 Schunck and Brebner, Annals of Botany, Vol. vi, p. 167. 
