MINUTE STRUCTURE OF PLANT HYBRIDS. 267 



Petals — (b) Wings. — Illustrations are given in Plate VIII. figs 13 a', b', c' . From these 

 it will be seen that the claw in C. purpureus is slightly shorter than the blade, in C. Adami 

 it is half as long as the blade, and in C. Laburnum rather less than one-third the length. 



Each wing in C. purpureus shows a twisted ridge on the claw which fits into a cor- 

 responding groove on the claw of each keel-petal to form a locking spring arrangement. 

 Along the upper edge, and to a less extent along the lower, there is a marginal fringe of 

 long simple hairs, the number of the former being 160 to 170, and of the latter 30 to 35. 

 The outer and inner epidermal cells are quadrangular-sinuous below, but gradually become 

 more elongated and angular-sinuous above, where they develop infoldings of the walls. 

 Their free surfaces are slightly convex. Each wing in C. Laburnum has a straight claw, 

 and the only connection with the keel-petal is by a bulging depression in each, which fits 

 the one into the other. The entire wing is destitute of hairs. The outer and inner 

 epidermal cells are quadrangular or polygonal below, but they become very slightly wavy 

 above, and their walls exhibit infoldings. The free surfaces of the cells along the upper 

 half of each wing grow out into papillae. Each wing in C. Adami has a decided tw r ist on 

 its claw, though it is not nearly so pronounced as in C. purpureus. Fringes of hairs 

 occupy exactly the positions that they do in C. purpureus, but in all cases these are less 

 abundant — thus one specimen had 130 along the upper margin and 14 below, another 76 

 above and 17 below, a third had 83 above and 15 below, and a fourth had 73 above 

 and 18 below. The epidermal cells are nearly polygonal below, but are almost exactly 

 like those of C. purpureus above. They are further like the last, and quite unlike those 

 of C. Laburnum in that they never form epidermal papillae, the free surfaces of the cells 

 being merely convex. 



Petals — (c) Keel. — As shown by figs. 13 a", b" , c" of Plate VIII. , the relation in length 

 the claw to the blade in the keel-petals is nearly in the same proportion as those of the 

 wings. In C. purpureus a fringe of long hairs, 100 to 110 in number, grow out along 

 the upper edge at the junction of claw and blade, and a long fringe of shorter feebler 

 hairs, 300 to 330 in number, line the lower edge. The inferior epidermal cells are poly- 

 gonal or rectangular and straight walled, but higher up they become elongate-sinuous. 

 In C. Laburnum each keel-petal is destitute of hairs. The inferior epidermal cells are 

 elongate and straight walled below, but higher up they become equiradial and sharply 

 angular, with infoldings of the walls. In C. Adami fringes of hairs in the same position 

 as those of C. purpureus line the margins of the keel-petals, but are half as abundant — 

 thus one specimen had 48 to 50 along the upper edge, and 152 to 155 along the lower, 

 another had 57 above and 148 below. 



Stamens. — The staminal tube of C. purpureus has two luxuriant lateral rows of hairs, 

 and less abundant median masses. These hairs, like many of those on the petals, are . 

 partly thin walled and uniform, partly provided with wart-like thickenings. The pollen- 

 cells of alcoholic material are of a yellow-brown colour, and each is 25 to 26 [i. The 

 staminal tube of C. Laburnum is entirely devoid of hairs. The pollen- cells are yellow in 

 colour, and each is 21 to 23 /t. In C. Adami the staminal tube has two luxuriant lateral 



VOL. XXXVII. PART I. (NO. 14). 2 Q 



