198 MISS WINIFRED SMITH ON THE ANATOMY 
any sign of lignification in the position of a central trace. The midrib of the cotyledon 
was formed as indicated in Pl. 26. fig. 10. The primary vascular bundles lie typically 
parallel to the cotyledonary plane, but are not intersected by it. 
3. Vascular system of the cotyledons :—The first differentiation of xylem is seen at 
the tip of the cotyledon and progresses downwards through the node. The two strands 
of metaxylem belonging to each double vascular bundle remain separate and are seen 
halfway between the cotyledonary node and the root-apex to be placed each side of 
the xylem of the primary root-strand. Protoxylem-strands of the cotyledon, if double 
above, fuse at the node and occupy a median position. In Bumelia tenax the protoxylem 
strands of the cotyledon are single and occupy a median position between the members 
of a double group of metaxylem. They are completely isolated by parenchyma in 
Payena Leerti, Bumelia tenaz, and Chrysophyllum Cainito. 
^4. Root system :—Lignification progresses from the node downwards, dying out 
gradually near the root-apex. The continuity of the protoxylem is sometimes inter- 
rupted for short distances, probably owing to stretching during growth. 
5. Stem system :—Differentiation of xylem begins at the node and progresses down- 
wards. In Bumelia tenax there is marked lack of continuity. The small spiral and 
annular tracheids belonging to the traces of the first internode do not reach to the node. 
This break is perhaps only an exaggeration of what is seen in the protoxylems of the 
root and to be accounted for by the rapid elongation of the shoot (see Bumelia tenaz, 
fig. 11 4). Asin Diospyros the foliar traces fork and spread out at the node in this 
species, and are represented by a reduced number of bundles above and below the node. 
6. Accessory system of the root:—In Bumelia tenax we moet with a number of strands 
not primary, which I have called the accessory system of the root. The strands which 
constitute this system do not correspond in number and position with the foliar traces 
which appear at the node. 
At the stages of development observed in the seedlings and seeds described the 
separateness of differentiation obtaining in these different vascular systems is very 
marked and clear. 
The impression derived from a study of these Sapotaceous seedlings is that, while there 
is a characteristic type of anatomy for the order, it is subject to adaptive variations as to 
number of strands primary and otherwise; but is constant as regards their structure, 
which in the primary strands is always dual. 
: nis work was done at the Royal College of Science and the germination of seeds and 
raising of seedlings was arranged for in the Chelsea Physic Garden. I need hardly say how 
invaluable it has been to me to work under the counsel and criticism of Professor Farmer. 
[NorE.— Since the above went to press, my attention has been drawn to M. Mattes 
paper * on the seedling anatomy of Ceratozamia and Stangeria. Me finds lack * 
continuity at the node and accessory root-strands, as I do in Bumelia; but he puts ? 
different interpretation on the facts —W. 8. ] 2 
[2 Feb., 1909.] i 
* Loc. cit. (cf. post, p. 199). 
