Notes. 
75 
extends about three-fourths of the way to the base, giving the spines 
a glistening appearance. The cells with lignified walls form a solid 
cap at the apex; below they are confined more and more to the 
superficial layers, forming altogether a hollow cone, thinning out 
towards the base. There is no trace of any ‘ epithema/ 
T read's figures of the ostioles strongly resemble the perforations 
of the leaves, which he states are due to insects. This, coupled with 
the fact that they do not occur constantly, points to the opening being 
pathological. The function of the spines is therefore probably only 
protective, the fibrovascular bundles, as in other emergences, being 
only present in the larger ones. The distribution of the spines shows 
that they must be for protection against some submerged animal of a 
fairly large size. 
J. H. BLAKE, Cambridge. 
THE LATICIFEEOUS TISSUE IN THE STEM OP 
HEVEA BRASILIENSIS. — The material used in this investigation 
formed part of some supplied by Dr. Trimen, from Ceylon, and con- 
sisted mainly of seedlings 21 to 25 days after their appearance above 
ground. Sections of younger seedlings were also examined. 
The work has been done under the advice and direction of Dr. 
Scott, and has been carried out in the Jodrell Laboratory, Kew. 
Distribution of the Laticiferous Tissue . In the hypocotyledonary 
and epicotyledonary stems of the younger seedlings laticiferous tissue 
is abundantly developed in the inner cortex but none was observed 
either in the outer cortex or in the pith. In older seedlings, however, 
medullary laticiferous tubes occur in the upper part of the first epicoty- 
ledonary internode, and in the succeeding internodes 1 2 . 
In most cases the medullary tubes seem to be connected with those 
of the cortex only at the node, but in one case a tube was distinctly 
seen running obliquely upwards from the cortex, passing between the 
vascular elements and continuing its course in the pith. This occurred 
at a short distance below the node. 
1 Cf. Scott, On the Laticiferous Tissue in H. spruceana y in Quart. Journ. 
Microscop. Sci., vol. xxiv. p. 206. Also in Journ. Linn. Soc. (Botany), vol. xxi. 
1885, p. 566. 
2 The first internode of the epicotyl in these seedlings measured 9-10 inches in 
length, and medullary laticiferous tubes were only found in the upper half-inch. 
The second intemode in no case reached half-an-inch in length. 
