260 
Birbal Salmi. 
The changes that occur at the base of the lateral plant are 
shown in Text-fig. 5. They comprise the origin of two stolons (5,, 
s 2 ) and two leaves (l t , l 2 ). The stolon bundles never leave gaps. 
Concurrently with the origin of the first stolon, two small strands 
are separated off from the central cylinder, one on each side of the 
stolon (D,, D 2 ) ; these form the dorsal strands of the two compound 
leaf-traces, there being no simple traces in the lateral plant. The solid 
central cylinder rapidly becomes horse-shoe shaped, ( c , d, d ’) by an 
invagination of the cortex, which pushes the endodermis, pericycle 
and phloem before it. The dorsal strand of the first leaf(-Dj) turns 
round so as to lie opposite the invagination. This small strand is 
clearly not responsible for the relatively huge gap which it subtends 
and which rapidly deepens, giving the cauline strand a distinctly 
horse-shoe like form as seen in section (d). In fact the dorsal strand 
does not contribute at all to the formation of the invagination. The 
latter presently breaks through to the opposite side of the horse-shoe, 
dividing it into two large curved strands (e, /). It is clear that this 
stage cannot be called a dictyostele, for the gaps are not leaf-gaps. 
From the ends of the large strands opposite D lt two relatively 
large ventro-lateral strands are constricted off, and these three 
together form the first leaf-trace (l t ) which is compound. 
It may be pointed out that by the separation of the two ventro¬ 
lateral strands, the gap, from whose sides they come off, becomes 
larger, and the first leaf-trace may, in a sense, be said to be 
responsible for a portion of the gap, though not for its initiation. 
A second stolon (s 2 ) arises exactly like the first and at the 
same time the second leaf-trace (l 2 ) is completed, exactly like the 
first. 
Before the first gap (that opposite the first leaf-trace) is closed 
up, the dorsal strand of the third leaf arises at a different point on 
the cauline stele, causing a distinct gap, and being followed at a 
higher level by its two ventro-laterals. A fourth leaf may soon 
arise similarly, so that the vascular structure at the apex of the 
lateral plant is a primitive form of dictyostele. 
Beyond a rough numerical correspondence there is not much 
to suggest any relation between the stolon and the leaves. The 
origin of a stolon is frequently, but not always (as shown by b\ d' 
in Text-fig. 5) along a radius at right-angles to the one on which 
the nearest leaf is situated. 
The stolons borne by the lateral plant, which may become 
tendril-like, are similar to the secondary stolons in internal structure. 
