Notes . 
335 
examination of the subject from several points of view. My apology 
for bringing forward the results in so incomplete a state is that, at 
present, I have not the time at my disposal to complete it, owing to 
my departure for the tropics, and that it may possibly prove sugges- 
tive enough to excite interest in the problem and so help in its 
solution. 
The work of Schullerus 1 , Treub 2 , and Faivre 3 is too well known 
to need description, as is also Schimper’s 4 criticism of it. 
Haberlandt’s work 5 is disputed, but as he still maintains his original 
views in the last edition of his Physiologische Pflanzenanatomie, 
I have thought it worth while to repeat it. 
In leaves in which the palisade-tissue is loosely packed, as in 
Euphorbia mellifera and Euphorbia punicea , frequent examples of the 
palisade-cells converging to the blind apex of a laticiferous cell, or 
a cell in direct connexion with it, can be met with. 
In Euphorbia spinosa, where the palisade-layer is double, the 
branches of the laticiferous tubes run between the two layers and send 
out terminal branches into the upper layer of palisade-cells, thus 
forming a kind of brush-work. The blind endings are usually on the 
upper surface of the palisade-cells. 
These terminations may be traced by mounting the sections in 
phenyl-hydrazine, the high refractive power of which renders it a very 
useful clearing agent. At the same time a marked staining action 
occurs in the palisade-cells and in the cells in which Fry 6 has 
described ‘ proteid aggregates/ which may be worth further in- 
vestigation. 
In laticiferous plants whose assimilation is carried on by the stem 
owing to partial or complete reduction of the leaf-surface, the 
assimilating cells form a compact layer several cells in thickness, 
e. g. Euphorbia arbor escens and coerulescens. The laticiferous cells 
pass directly through this layer and end, for the most part, on the 
upper surface of the outermost layer of assimilating cells. 
Taking all observed cases into consideration, I think we may safely 
1 Schullerus, Abhandl. d. bot. Vereins d. Prov. Brandenb., 1882. 
2 Treub, Anns, du Jardin Bot. de Buitenzerg, vol. iii, p. 37. 
3 Faivre, Ann. des Sci. Nat., ser. 5, t. x. p. 33. C. R. t. lxxxviii. p. 269, etc. 
4 Schimper, Bot. Zeit, 1885, p. 771 et seq. 
5 Haberlandt, Sitzb. d. k. Akad. Wien, 1883, p. 51. 
6 Fry, Annals of Botany, Vol. v, p. 413. 
