240 DR J. M. MACFARLANE ON THE 



i. Menziesja \;\t\\ glandular hairs composed of a delicate stalk and large globular head, while in 2 the 



enipetritornus, © x ° ° 



J ar - glandular hairs are wanting, but the curved hairs are present, though shorter and about 



t. Bryanthns ° ° r o 



erectus. one-third as abundant as on the first. Along the line of leaf revolution in 3 there are 



3. Rhododendron ° 



chamrecistus. elongated compound pointed hairs, exactly resembling others which are marginal in position 

 and terminate the leaf serrations, except that a few of the latter may terminate in a small 

 knob. In 1 the line of leaf revolution develops shortly-stalked greenish gland hairs. In 

 2 there are short glandular hairs similar in position and appearance to those in 3, though 

 slightly longer in the stalk, and the latter peculiarity, I take it, is derived from 3. The 

 compound marginal hairs of 3 are absent. We have here, therefore, the curious condition 

 on the lower epidermis of gland hairs belonging to one parent, and marginal hairs 

 belonging to another, being alike undeveloped in the crossed offspring. 



Transverse leaf sections are very striking in their relative outlines and depth of 

 tissue. 



Flower Parts. — A series of measurements were made of the flower-stalks, and other 

 parts in the three, and the average results are given below. In 3 the length of the 

 flower-stalk is f to § in. ; in 2, |- to 1 in. ; and in 1 it is 1^ in. The number of flowers in 

 a cluster are 2 to 3 in 3, 4 to 7 in 2, and 8 to 14 in 1. 



Sepals. — These in 3 are short, broadly ovate, red or rarely red-green in colour, and 

 overlap each other considerably at their bases. In 2 they are ovate-acuminate, overlap 

 less than in the last, and are greenish-red, while in 1 they are lanceolate-acuminate, 

 scarcely touch at the base when expanded, and are reddish-green in colour. 



The average size of the epidermal cells in the sepals of the hybrid are very exactly 

 intermediate, though at times they may vary over small areas. The structure and 

 distribution of hairs is again worthy of special note. In 3 each sepal shows externally 

 over its base simple curved hairs, with slightly warted surface markings, and over the 

 general surface a few glandular hairs whose stalk is long and made up of cells which are 

 unevenly placed and taper into each other by oblique ends, while the terminal knob is 

 elliptic in shape. In 1 each sepal shows a very few simple hairs at its apex only; 

 glandular hairs, whose stalk- cells are short and arranged in transverse rows, and whose 

 apex is oval or nearly spherical in outline, occur sparingly over the outer surface. The 

 hybrid (2) possesses a few simple though shorter hairs round the apex of the sepal, 

 as in 1, while both types of glandular hair occur promiscuously, though in no case 

 abundantly. 



On transverse section the sepal of 3 shows an extremely fine cuticular ridging, that of 

 1 has it much more developed, while the most careful measurement gives an intermediate 

 amount in the hybrid. The mesophyll of 3 consists of three thinning out into two 

 layers of chlorophyll cells, that of 1 shows four, while the hybrid shows three which 

 become rather small and irregularly packed at their edges. 



Corolla. — The corolla of 3 is salver-shaped, the petals are deeply divided, and each is 

 slightly coucave internally. The colour is pale pink below, shading into a more delicate 

 hue above. The corolla of 2 is tubular below, becoming slightly salver- or cup-shaped 





