194 MR. P. GROOM—CONTRIBUTIONS TO THE 
by the breaking-down of all the vessels save a circle of narrow 
annular vessels with few widely separated annuli. In the outer 
bundles this disorganization takes place to a considerably less 
extent. The bundles have no sheaths of sclerenchyma. Thus 
there is, as inthe rhizome, a complete absence of mechanical tissue; 
the walls of all the cells are delicate and composed of unmodified 
cellulose, with the exception of the thin cuticle on the epidermis 
and the lignified walls of the insignificant bundles of xylem. 
Histology of the Scales on the Inflorescence-azis. 
I had at my disposal only the portions of the axis below the 
attachment of the flowers, and hence cannot describe the 
histology of the bracts. A scale which is above the ground 
displays the following structure :—It is composed of a lower 
(outer) epidermis, about five layers of mesophyll, and an upper 
(inner) epidermis, more or less applied to the axis. The epidermal 
cells have delicate walls and are longitudinally elongated and 
narrow—much longer and narrower than those on the subterranean 
scale. There are neither hairs nor stomata. Cuticle on the 
outer epidermis is very thin, and is all but imperceptible on the 
inner epidermis. The elongated cells comprising the mesophyll 
have tolerably developed intercellular interstices and slender 
walls; amongst them are numerous larger, elongated, raphide- 
mucilage sacs, which are most abundant close within the outer 
epidermis. These sacs are more abundant than in corresponding 
parts of the axis (cf. Galeola). 
The vascular bundles which enter the scales are small and 
simple, the conducting aylem being represented by 2-3 fine 
annular or spiral vessels, and the phloém being composed of a 
little mass of parenchyma and very narrow elongated elements, 
in which I could detect no differentiation into sieve-tubes and 
companion-cells. No starch occurred in these scales. Again, in 
the scales there is a complete absence of mechanical tissue. 
Ascending from the rhizome to the floral region, it will be noted 
that the scales become narrower and relatively longer. And 
the transition from the subterranean scales to the aerial ones 
is histologically a gradual one. At the extreme base of the 
inflorescence-axis the scales overlap one another and the portions 
which are overlapped have no hairs, but the free apical parts of 
these scales have long hairs on which particles of humus cling. 
On the scales which are inserted upon the aerial part of the axis 
