440 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
In another article * * * § M. Chauveaud reviews the various theories that 
have prevailed with regard to the function of sieve-tubes, and sums up 
in favour of the view that their primary function is that of the transport 
of food-material. 
Laticiferous Tubes and Sieve-Tubes of Cuscuta.f — The laticiferous 
tubes and sieve-tubes of the monogynous species of Cuscuta have been 
made a subject of study by M. M. Mirande, Cuscuta monogyna and 
japonica having been the species especially examined. The laticiferous 
tubes are situated in the cortical parenchyme and in the pericycle, and 
are never connected by anastomoses. Those in the cortex are long 
superposed cells ; those of the pericycle occupy the whole length of the 
internodes, and have thickened walls. They contain oily matters, 
tannin, and a resinous substance. The sieve-tubes are remarkable from 
the diversity of their structure, and from their large size. The transverse 
walls are horizontal or oblique, and are sieve-plates ; the longitudinal 
walls also containing sieve-plates or punctations of various sizes, or both. 
The sieve-tubes (in C. japonica) do not contain starch, but an amylaceous 
substance stained red by iodine. 
Mucilage-Cells of the Malvacese4 — Dr. A. Nestler describes the 
mucilage-cells in the leaves of various species of Malvaceae, which he 
regards as organs for the absorption and retention of water. They are 
epidermal cells, the cuticle of which projects into the interior of the cell 
in the form of a conical or funnel-shaped mass, giving the cuticle the 
appearance from the outside of being perforated. The nucleus is 
situated near the mouth of the funnel. It is the inner and lateral walls 
of these cells which become converted into mucilage. The author finds 
hsematoxylin (Bohmer’s) to be the best reagent for demonstrating the 
mucilage-cells, imparting to them a deep blue colour. 
Mucilage-Cells of Qpuntia.§ — Sig. Longo has made a study of the 
mucilage- cells in Opuntia, and states that they are distributed through 
the fundamental parenchyme of all parts of the plant. The mucilage 
does not result from a transformation of the cell-wall, but is a direct 
product of the cell-protoplasm. Their function is that of a water-tissue. 
Cells containing crystals occur in the branches and fruit of Platopuntia , 
but are absent from Cylindropuniia. 
C4) Structure of Org-ans. 
Flower of Deherainia.|| — Dr. G. Fatta has made a study of the 
flowers of DeJierainia smaragdina , a shrub belonging to the MyrsineaB, 
from Mexico. The flowers remain expanded for a period reaching to 
20 days, and are strongly proterandrous, the pollination being effected 
by carrion flies. The petals remain green and coriaceous during the 
whole time of flowering, and apparently take no part in assisting polli- 
nation. They contain chlorophyll, but this chlorophyll appears to have 
entirely lost its power of forming starch and of 'assimilating. On the 
* Rev. Gen. de Bot. (Bonnier), ix. (1897) pp. 427-30. 
f Journ. de Bot. (Morot), xii. (1898) pp. 70-90 (8 figs.), 
j Oesterr. Bot. Zeitschr., xlviii. (1898) pp. 94-9 (1 pi.). 
§ Ann. R. 1st. Bot. Roma, vii. pp. 44-57 (1 pi.). See Amer. Naturalist, xxxii. 
(1898) p. 214. || Nuov. Giorn. Bot. Ital., v. (1898) pp. 145-57 (1 pi.)- 
