252 MR. Е. E. WEISS ON THE CAOUTCHOUC-CONTAINING 
Тһе caoutchoue-containing cells of Eucommia are unbranched and still contain only 
one nucleus, but it is easy to conceive that a division of this nucleus into several 
younger nuclei, a division which might become necessary by the dimensions of the cells, 
would enable the cell under certain conditions to branch out in other directions, as it has 
become normal for the latex cells of the Euphorbiacee. 
But the faculty of branching having been acquired, and their powers of growth having 
been increased by their multinucleate condition, the number of these cells might very 
naturally become reduced. Such reductions are of frequent occurrence in the vegetable 
kingdom. І need only cite the reduction which takes place from multisporangiate leaves 
to unisporangiate forms among the Cryptogams, and the reduction of the number of 
archegonia which has taken place in the phylogeny of the Gymnosperms and Angio- 
sperms. 
There is also, both in the vegetable and in the animal kingdom, the well-known 
tendency of “anticipation,” which for example, in the group of vascular Cryptogams, 
has caused the differentiation of sexes to be anticipated by the heterosporous forms in 
the sporangium, while the more primitive homosporous forms do not show that 
differentiation until the prothallium is developed. 
This same tendency has, I think, in the evolution of the laticiferous cells, caused the 
embryo to produce these laticiferous cells, and their formation from cells in older 
tissues has become unnecessary, by reason of their excessive growth and vitality, very 
much as Pax suggests. 
The occurrence of closed latex sacs in the adult plant in Aleurites and Jatropha, for 
which Chauveaud has described non-articulated latex cells in the embryo, may indicate 
merely the retention of the older form of laticiferous tissue by the adult plant, while the 
latex cells which are to supersede the closed sacs are found already starting, and at least 
supplying the embryo. 
Whether Eucommia has initial cells іп its embryo similar to those of Euphorbia or not 
we have no means at present of ascertaining, but I would like again to mention that these 
cells in Euphorbia often occur in pairs, and then present all the appearances of the 
initial cells in the cortex of Eucommia. I incline to the belief that the embryo 
of Eucommia has no such cells, first on the ground that they would be unnecessary to а. 
plant which is so well provided with other cells in its new organs, and, secondly, because 
these caoutchouc-containing cells do not arise in meristematic regions, but in a secondary 
manner, in tissues which are far progressed towards maturity. 
The function of the caoutchouc-containing cells, as far as the preceding observations go, 
cannot be in any way connected with the conduction of food substances ; for they are 
closed cells filled with a solid mass of caoutchouc, which would prevent the passage of 
food substances as effectually as a callus plug. Their presence in large number in the 
leaves might suggest the idea that they conduct away substances formed in the leaf, but 
they terminate not so much in the assimilating layer as at the margin of the leaf, which 
would be much more suggestive of some sort of protection against insects or other 
animals, to which the caoutchouc might prove distasteful. Their occurrence, too, in the 
middle of the pericarpal wall in such large numbers would support this theory. If the 
