Holden and Bexon.—Observations on the 
5*6 
relation to the extent of fission, for it may occur at approximately the same 
level in a cotyledon showing an apical notch, as in one which has a deeply 
split lamina, the union taking place in both instances in the cotyledon 
petiole. Even when the two half bundles are a little more widely separated 
Fig. 3. a-e. Hemitricotyl, Type a. Diagrams showing the characteristic features of this type. 
Fig. 4. Hemitricotyl, Tvpe P. Transverse section. Petiole. 
Fig. 5. Hemitricotyl, Type P. Transverse section near apex of hypocotyl. 
FIG. 6. Hemitricotyl, Type P. Transverse section near base of hypocotyl. • 
ph = phloem ; px = protoxylem. All three figures show a considerable development ot 
secondary xylem. 
at the node than in the normal double bundle, the rotation still occurs at 
the usual level. . 
(b) The second group of hemitricotyls comprises two seedlings only, 
and in these the vascular strands of the abnormal cotyledon show consider¬ 
able differences in structure and behaviour compared with those of the first 
