248 МЕ. Е. E. WEISS ON THE CAOUTCHOUC-CONTAINING 
observers, have shown to contain numerous nuclei. Тһе unbranching character of the 
cell would not, however, preclude the existence of several nuclei, as Treub has shown 
that many unbranched bast-fibres have several nuclei. "Though therefore а ramifying 
cell, such as a latex cell, requires several nuclei for its continuous growth, which seems 
to last during the entire life of the plant, an unbranched but very extensive cell may 
also have several nuclei, and it is no doubt the presence of several nuclei which has 
enabled the branching cell to be evolved from the non-branching one. 
The caoutchouc-containing cells of Hucommia are therefore simpler in structure than 
the latex cells of the Euphorbiacez, and would also appear to be more primitive than the 
multinucleate fibres described by 'Treub. 
The nucleus of the caoutchouc-containing cells in the early stages is elliptical or 
round, usually containing one large nucleolus, but in later stages it becomes spindle- 
shaped, and often, in fact, generally, possesses two large nucleoli. The fact that the 
nucleus remains in its initial position, and is of considerable size, almost touching the 
cell-wall on either side, is an additional support to the purely negative evidence, which 
has led me to the conclusion that only a single nucleus is present in these cells. 
As the ends of the initial cells grow out, they make their way upwards and down- 
wards along the path of least resistance, $. e. along the intercellular spaces. Ав these 
are, however, large and numerous, the course of the cells is fairly straight (fig. 8). But 
usually the two sister cells become separated by the obstacles they meet on their course, 
and even at so early a stage as that represented in fig. 6, though the caoutchouc- 
containing cells run in pairs, yet most sister cells are separated by considerable intervals. 
They can, however, usually be matched in couples. This becomes more difficult in the 
later stages, as is apparent from fig. 7. | 
Тһе growing end of the cell is often curiously dilated into a bulbous termination, 
similar to those described by Schmalhausen for the ends of the latex cells in the root 
of Euphorbia embryos. But Schmalhausen speaks of a tapering end behind which the 
actual dilatation occurs, whereas those of the caoutchouc-containing cells of Hucommia 
terminate bluntly with the bulb. Schmalhausen’s observations gave him the impression 
as though it were only with difficulty that the latex cell could find room, between the cells, 
to push in its apex, and that it endeavours by extension to fill up all possible cavities. 
The dilatations I have observed in many cases, however, could have no such cause, 
as they were found in the middle of wide intercellular spaces (fig. 10). Immediately 
behind the apex, the walls, usually thin and delicate, are considerably thickened (fig. 10). 
In some of the bulbous terminations the contents were still of a granular nature, and 
had not yet coalesced into a solid mass, characteristic of their final state. In these cases 
the bulbous terminations contained a certain amount of substance, staining deeply with 
protoplasmic stains, and there is no reason to suppose that these cells were unable to 
continue to grow. In others, however, the contents were already fused into a solid mass - 
of homogeneous caoutchouc, and little or no protoplasm could be observed, so that a 
considerable diffieulty would lie in the way of our considering these as actively growing 
ends. I would suggest, therefore, that these dilatations, when they occur in such positions 
as that figured in fig. 10, indicate that the limit of growth of one of these cells has been 
