5i4 
Holden and Bexon.—Observations on the 
Methods. 
The seedlings were uprooted at as early a stage as possible, and were 
preserved in methylated spirit. Considerable difficulty was experienced in 
finding a stain suitable for the very delicate seedlings. Although numerous 
combinations of stains were tried, Delafield’s haematoxylin was the only 
reagent whfch gave satisfactory results. At a later stage in the investiga¬ 
tion, however, when the more robust seedlings of the garden variety were 
microtomed, good results were obtained with carthamin in 70 per cent, 
alcohol, followed by Lichtgriin in clove oil. 
Description of Results. 
The structure of the normal seedling of Cheiranthus Cheiri has been 
fully described by Miss Thomas (20), so that no detailed account need be 
given here. 
The slender seedlings show, in every case, a high level of transition. 
The base of each cotyledon is occupied by a central * double ’ bundle, 
which in the transition region ‘rotates’ 1 to form one pole of the diarch 
root. With this brief summary we may proceed at once to the description 
of forms showing more or less pronounced polycotyly. 
Hemitricotyls* 
The nine seedlings of this type which were examined showed all 
stages of hemitricotyly, ranging from forms with only a slight notch at the 
apex of the abnormal cotyledon, to others showing fission right to the base 
of the lamina (Fig. 1). Usually the two halves of the bifurcated cotyledon 
were together of approximately the same size as the normal cotyledon 
(Fig. 1, a), but in one or two instances each half was as large as a whole 
cotyledon (Fig. 1, b). 
One case of considerable interest showed a peculiar asymmetry in the 
methods of fusion of the two halves of the cotyledon (Fig. 2). One half 
retained the leaf tissues on both sides of the midrib, whilst the other 
gradually lost its tissues on the side nearer its fellow, so that at the point of 
junction of the two halves an irregular Y-shaped structure was formed. 
This, however, soon became symmetrical by the dying away of the extra 
flange. 
The behaviour of the vascular bundles of the hemitricotylous seedlings 
is extremely interesting, and enables one to divide them into two distinct 
groups. 
1 The terms ‘ transition ’ and * rotation ’ are used in this paper as convenient conventionalities 
•without implying adherence to the theories of seedling structure in which they originated. 
