On Caoutchouc in Plants. 
29 
that they may arise by differentiation and stretching of ordinary 
parenchymatous cells, which in their later elongation push their way 
in and out between the surrounding cells. The tortuous course 
of the caoutchouc elements in the secondary cortex of the above- 
mentioned Hippocrateaceae seems very suggestive of such an origin. 
It is perhaps a little premature to talk of the phylogenetic 
importance of this type of laticiferous element; but so much may 
be pointed out, that the occurrence of unbranched latex-cells (sacs, 
confined to the axis and of determinate length) and of branched 
laticiferous elements (occurring throughout the plant and attaining 
a great length), in species of the same genus tends to support the 
views, expressed by Weiss. 1 This investigator looks upon Eucommia 
as possessing “ a primitive, though not the most primitive form of a 
latex-cell.” He further remarks : “The caoutchouc-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 Euphorbiaceae.” Should a more detailed 
investigation show that the unbranched latex-cells of Hippo¬ 
crateaceae contain only one nucleus whereas the branched elements 
are multinucleate, 2 the phylogenetic connection suggested by Weiss, 
will be fully established. In their late appearance and their 
restriction to the axis the unbranchcd caoutchouc-cells of the 
Hippocrateaceae and of Evonymus seem to be more primitive chan 
those of Eucommia. 
It might be imagined that the laticiferous cells (sacs), found in 
Evonymus, etc., gradually began to make their appearance at an 
earlier stage in the development of the plant and also to extend into 
the lateral appendages; in this way the type of latex-cell, found in 
Eucommia, may have originated. Multiplication of the nuclei in a 
laticiferous element of this type would tend to produce an increase 
in size of the element in question and ultimately lead to a certain 
amount of branching taking place. Under these circumstances the 
number of the individual latex-cells could be considerably diminished. 
We thus reach the type of laticiferous element, occurring in many 
Euphorbiaceae and in the Apocynaceae, Urticaceae, etc. This 
evolution of the branched from the unbranched type has, as is 
1 loc. cit. p. 251, 252. 
J Attempts to stain the nuclei have as yet proved unsuccessful. 
