738 
Lee. — Observations on the 
wood, the midrib of the seed-leaf was conspicuously bicollateral in structure. 
In all cases the transition was according to Type 3, and the internal phloem 
died out in the root. 
Scrophulariaceae. 
Verbascum pulverulentum , Vill. Seedlings about two centimetres 
long, with definite hypocotyl and two unequal cotyledons. Each cotyle- 
don consists of a large lamina which passes gradually into the definite 
petiole. There is no cotyledonary tube. 
In the lamina the midrib sends out small branches, but enters the 
petiole as a single rather small vascular bundle. The rearrangement of the 
vascular tissue begins before the strand enters the hypocotyl, and is com- 
pleted very quickly. The transition, which is according to Type 3, is 
masked by the presence of two epicotyledonary traces situated in the 
intercotyledonary plane, which persist throughout the hypocotyl and enter 
the root. Thus for a long distance in the upper part of the root the 
arrangement appears to be tetrarch when it is really diarch, a condition 
which is indicated by the origin of the lateral rootlets. These are given off 
in four rows from the two ends of the diarch plate. 
Alonsoa . As described by Dangeard ( 5 ) the transition in this genus 
appears to conform to Type 3. 
Diascia Barberae , Hook. In most Scrophulariaceae examined, the 
rearrangement of the vascular tissue begins in the upper part of the petiole, 
and one of the first indications is the separation of the xylem strand into 
three more or less definite portions, of which the median one is the proto- 
xylem. In D. Barberae the xylem remains throughout quite continuous. 
In the upper part of the petiole, the vascular bundle divides into two parts 
(Diagram 6 , Figs. 1 and 2) connected towards the upper surface by means 
of protoxylem elements. Each semi-strand possesses its own phloem mass. 
The transition takes place by the passage of the phloem groups to a position 
in the intercotyledonary plane, where they fuse with their fellows from the 
other seed-leaf, and by a simple twisting on the part of the xylem, so 
that the protoxylem takes up an external position (Diagram 6, Fig. 3). 
Lin aria or ierani i folia. DC. ) T . . . - . 
_ . . _ ^ „ _ r f In both species the minute seedlings are 
Linana heterophylla^ Desf.J 
provided with two equal petiolate cotyledons. There is no cotyledonary tube. 
The transition, which is according to Type 3, commences in the petiole, 
and takes place very quickly. 
Nemesia jtoribunda , Lehur. 
Nemesia versicolor , E. Mey. 
the seedlings of these species are exactly like those of Linar ia. The method 
of transition is the same, and the rearrangements take place in the upper 
part of the hypocotyl. 
With the exception of their larger size, 
