788 Transactions of the Society. 



their outward aspect ; but sections of them exhibit a far more com- 

 plicated structure than their outward form would lead us to expect. 

 Figs. 1-3 represent sections in as many directions, No. 1 being 

 transverse, 2 tangential, and 3 longitudinal and radial with regard 

 to the stem. 



The sections show that these organs are so developed as to 

 enclose a number of chambers, having communication externally at 

 their base. These chambers are produced by the early, unequal, 

 and excessive development of what is morphologically the under 

 side of the lamella of the leaf, the epidermis being continuous over 

 their entire inner surface. Their number and form is very variable, 

 and they frequently communicate with each other. 



The whole of the inner surface of these chambers is literally 

 crowded with glands, of which there are two forms, — a sessile gland, 

 three views of which are shown in Figs. 4-6, and a pedicellate gland. 

 Figs. 7, 8. The first form is composed of four cap-cells arranged 

 parallel to each other, and a large basal cell, which appears as an 

 annulus round the cap-cells, when the gland is looked at in plan or 

 perspective. Figs. 4, 5 ; Fig. 6 being an optical section, showing 

 peculiar thickenings of the walls of the cap-cells at four out of the 

 five angles formed by their union with the basal cell. The lower 

 wall of the latter, where it is in contact with the deeper cells of the 

 leaf, exhibits a large number of simple pits, rendering it almost 

 sieve-like in appearance. The other form of gland has a pedicel 

 usually consisting of a single cell cut off from the epidermal ceil 

 from which it originated by a septum, and a glandular head of two 

 or four cells, the cell plates which form them being always laid 

 down vertically and at right angles to each other. Occasionally 

 one of these glands may be found having a pedicel of two, three, or 

 four cells in vertical series, while others have a head of only three 

 cells, the division of one of the primary daughter-cells being sup- 

 pressed. 



Both kinds of glands are filled with a colourless, hyaline proto- 

 plasm, in which usually a few granules are included, frequently 

 exhibiting vigorous Brownian movement. 



On the surface of both forms of glands in the older scale-leaves 

 a large number of rigid, rod-like filaments are to be seen standing 

 at right angles to their surfaces, the nature of which I have not 

 been able to determine. They do not appear to be protoplasmic in 

 their character, as they do not shrink under the application of 

 alcohol, and are not continuous with the cell- contents. In young 

 leaves they are absent. In the older leaves the glands are also 

 always found surrounded with an accumulation of flocculent matter. 



The vascular system of the leaves also requires notice. The 

 common bundles, upon entering the leaves, divide at once, their 

 primary branches passing up between the chambers, where they 



