in the pith of Manihot Glaziovii . 6 1 
It appears therefore that here, as in other plants with lati- 
ciferous vessels, the latter retain their living contents after 
maturity. 
The material for the investigation was kindly supplied from 
the Royal Gardens, Kew, and the work was almost entirely 
carried out in the Jodrell Laboratory. 
EXPLANATION OF FIGURES IN PLATE V. 
Fig. i. Transverse section through part of a young stem, pr.xy. protoxylem, 
xy. xylem. p. pith. /. laticiferous tubes, three of which branch transversely, elf. 
* cambiform.’ (x 170.) 
Fig. 2. Portions of tangential sections, showing part of a complicated network 
of medullary laticiferous vessels (Z) with some of the surrounding pith-cells. ( x 1 50.) 
Fig. 3. Portion of a nearly radial section. Z laticiferous vessel, pr. xy. proto- 
xylem. Between the spiral vessel and the laticiferous tube are two layers of pith- 
cells, the ‘ cambiform ’ cells being absent here. ( x 150.) 
Fig. 4. Longitudinal radial section through part of the node of a stem where 
secondary thickening has made some progress, xy. xylem of part of the stem. 
If. bd. bundle passing out to leaf, lig.p. lignified parenchyma-cells with pitted walls. 
p. ordinary thin- wailed pith. /. laticiferous vessels. At a. the tube was not quite 
distinct, as it dipped below the plane of the section. ( x 80.) 
Fig. 5. Diagram showing arrangement of the various laticiferous systems in 
a transverse section of a young node. If. bd. leaf-bundle, hd. 1 . hypodermal latici- 
ferous system, sc. sh. sclerenchymatous sheath, ph. 1 . laticiferous system of the 
primary phloem, v. b. vascular bundle, cb. interfascicular cambium, m. 1 . medul- 
lary laticiferous system. 
Fig. 6. Diagram showing arrangement of the laticiferous tissue in a longitudinal 
radial section through half a node of an older stem. If. sr. leaf scar. If. bd. leaf 
bundles, xy. xylem. p. pith. hd. 1 . hypodermal laticiferous system, ph. 1 . lati- 
ciferous systems of two phloem-zones, m. 1 . medullary laticiferous system, lig. p. 
lignified parenchymatous cells with pitted walls. 
Figs. 7 & 8. Portions of an approximately radial section through the pith of a 
young internode, after treatment with ether, and staining with haematoxylin. 
/. v. laticiferous vessels : the contracted contents have a definite outline, and several 
nuclei n. are seen. Nuclei are also shown in some of the parenchyma-cells. At a, 
