740 
Lee. — Observations on the 
Antirrhinum Orontium , but the region of transition is shorter, and is 
confined to the upper part of the hypocotyl. 
Tetranema mexicanum , Benth. As in Mimulus lute us. 
Zaluzianskya capensis , Walp. Seedlings differ in no respect from those 
of Mimulus luteus . 
Veronica longifolia. L. , . , _ 
Veronica hederaefolia, L.j (als ° descnbed b 7 Gerard ( 7 > P- 37«))- 
Exactly similar to Mimulus luteus. . 
Rehmannia angulata , Hemsl. Both externally and internally similar 
to Linar ia origanifolia . 
Digitalis ferruginea , L. 
Digitalis lanata, Ehrh. 
Seedlings are much larger than in Antir- 
rhinum Orontium , and consequently the vascular tissues throughout are 
more definite. There is, however, no essential difference in the transition 
phenomena of these three species. 
Bignoniaceae. 
Incarvillea Delayvei , Bur. et Franch. Seedlings large, with two slightly 
unequal cotyledons. Hypocotyl long and fairly stout, with a prominent 
swelling at the point of attachment of the cotyledons, where also a distinct 
cotyledonary tube is formed. Apart from this and the presence of peculiar 
glandular hairs, the seedlings are very similar to those of Convolvulus . 
In the seed-leaves the mesophyll tissues are well differentiated. Each 
lamina has a large midrib, which is half-moon-shaped in section, and which 
gives off numerous branches in regular order (Diagram 7, Fig. 1). All the 
branches fuse with the median strand before the latter enters the long 
petiole, and as no further branching occurs a single laterally elongated 
bundle passes into the hypocotyl from each cotyledon (Diagram 7, Fig. 3). 
Previous to entering the hypocotyl, and often before the cotyledonary tube 
is reached (Diagram 7, Fig. 3), the phloem of each bundle bifurcates. In 
some cases also, the xylem shows distinct division into a middle portion 
consisting of protoxylem, and two lateral parts in close connexion with the 
phloem groups, and consisting of metaxylem with a few protoxylem 
elements (Diagram 7, Fig. % a). This condition, interesting for comparison 
with other species, is not constant ; it was found in one specimen, and even 
there did not persist for very long. In all cases, in the upper part of the 
hypocotyl, there are two bundles of xylem each with a single protoxylem 
group (Diagram 7, Fig. 4), and the rearrangements that now occur take 
place very gradually. As each bundle passes down the hypocotyl, its 
protoxylem divides into three, each branch at first consisting of 1-3 ele- 
ments (Diagram 7, Fig. 5, and PI. LXVIII, Fig. 3). The middle one passes 
almost directly outwards and takes up an exarch position in the plane of the 
cotyledons. The lateral groups traverse an oblique path, and finally come 
