204 
Harriet E. Allison. 
NOTE ON THE VASCULAR CONNECTIONS OF THE 
SPOROCARP IN MARSILIA POLYCARP A. Hook & Grev. 
By Harriet E. Allison, B.Sc. 
(Carnegie Research Scholar, Glasgow University). 
[Plate III]. 
HE sporocarp of Marsilia has been regarded as a ventral lobe 
of the leaf by Van Tieghem (6), but Dr. M. A. Chrysler (3) 
figures a section through the petiole of Marsilia quadrifolia Linn, 
at the point of attachment of the stalk of the sporocarp, showing 
that the origin of its vascular supply is from one edge of the curved 
leaf-trace. Goebel (4) has studied developmentally and described 
how in another species, Marsilia poly car pa, several sporocarps arise 
in acropetal succession on one side of the petiole. As the vascular 
connections in this species have not yet been described or figured, 
it was thought that it would be worth while to make observations 
upon it, so Professor Bower handed over to me material which he 
had received some years ago from Jamaica. 
In Marsilia polycarpa the petiole bears a varying number of 
sporocarps, usually from four to nine, arising acropetally on one side 
of the petiole, while the distal lamina is, as in Marsilia quadrifolia 
divided into four lobes. 
In the rhizome of M. polycarpa, a typical solenostelic condition 
is found. It has an outer cortex with air-canals, as in the petiole, 
separated from the inner cortex by a band of sclerenchyma. The 
vascular system consists of a continuous ring of xylem, in most 
parts two cells deep, surrounded by phloem and pericycle both on 
the exterior and interior, with a prominent external and internal 
endodermis. In the central part of the pith a small mass of 
sclerenchyma is present. At the insertion of the petiole the 
solenostele begins to elongate, the outer endodermis extending into 
the petiole base, followed by the xylem and inner endodermis which 
thus form a loop. Finally the xylem breaks off at one side, and the 
endodermis curves into the gap, which is soon completely closed by 
the joining up of the xylem. 
The structure of the petiole corresponds to that shown by 
Campbell (2) for M. quadrifolia. The leaf-trace consists of a V- 
shaped xylem strand, surrounded by phloem and pericycle. The V 
