658 Proceedings of Royal Society of Edinburgh. [sess. 
there are, at this level, eight hypocotyledon bundles and twelve 
others, the result of branching (fig. 11). The subsequent history 
of these bundles is as follows: — At about 15 cm. from the collet, 
the twelve bundles unite two and two, and the single bundles 
formed from these fusions take up an intermediate position be- 
tween adjacent main hypocotyledonary bundles. 
Just above this level, however, there is given off from each of 
the bundles 2 and 6 one small branch which takes up a position 
midway, i.e ., in the plane of the cotyledons, between bundles 2 
and 3 and 6 and 7 (a, /3, fig. 12). In some other specimens 
bundles 3 and 7 also contributed branches to a and /3 , hut these 
were much less important than those from 2 and 6. The bundles 
a and (3 are much smaller than the other similarly situated six, 
and continue unhranched until just below the point of insertion of 
the cotyledon petioles ; there they each break up to three or more 
reduced bundles (fig. 14 and fig. 8), which leave the central ring 
and form the vascular system of an axillary hud found in the 
axil of the cotyledon, and sometimes attached to the axis of the 
plant, sometimes to the cotyledon petiole. 
To return to the other six united branch bundles, at about 
15 cm. from the collet (fig. 8, X, Y), these divide again, each 
giving off two lateral branches (fig. 13). About 2 cm. higher up 
the original eight hypocotyledonary bundles begin to move out from 
the central ring, four supplying each cotyledon petiole. These 
eight bundles take with them to the petioles eight arcs of starchy 
endodermis, together with the small-celled conjunctive surrounding 
each (“ external conjunctive ” of Flot). 
The four bundles of each cotyledon petiole branch on either 
side. These branches run obliquely up the petiole and anastomose 
as indicated in fig. 15. At the lateral margins of the petiole two 
longitudinally running bundles are formed as a result of the 
anastomosis. Fig. 15 represents the branching and anastomosis 
as taking place in one plane, while in reality it occupies a length 
of several millimetres, and occurs irregularly so that a symmetrical 
arrangement is never seen in any given section. 
Precisely the same branching was made out in the cotyledon 
petioles of a very young germinating plant (of which a microtome 
series was cut), whose cotyledons were still within the testa. 
