190 MISS WINIFRED SMITH ON THE ANATOMY 
Mimusops Elengi. | 
Mimusops Kauki. V OF tis |‘ Miencopes:. 
Mimusops Schimperi. | 
Imóricaria coriacea. 
I propose to take Rayena Leerii as a type and describe and illustrate it with some 
fulness, and then to indicate in what points the other species agree with the type or 
depart from it. 
Payena Leerii has a large seed, measuring 27 mm. in length, 9 mm. in greatest width, 
and 7 mm. in greatest thickness. Its horny testa encloses a bulky endosperm, which 
covers the embryo completely except the tip of the radicle, which projects about a 
millimetre. The cotyledons are flat and about 0°6 mm. thick; they contain abundance 
of an oily substance. The endosperm is packed with starch. The plumular bud is 
represented only by a tiny cone of meristemmatic tissue. The embryo is extraordinarily 
precocious in development and assists much in the interpretation of the seedling. This 
was the more convenient as none of the seeds of Payena Leerii germinated, and I had 
no seedling which measured less than 8 cm. from the cotyledonary node to the 
root-apex. 
The future stele is represented in transverse section of the radicle by a rectangle with 
the corners cut off. The sides of this figure are formed of desmogen, easily recognizable 
by its small cells and deeply staining nuclei. At the corners are narrow tracheids which 
oceupy the position of the protoxylems of the seedling. In a seed with radicle about 
1:67 mm. long, the tracheids die out about -67 mm. from the node; while the latex-cells 
die out nearly a millimetre lower. At the node, on each side of the narrow tracheids, 
larger xylem elements appear, the three groups forming a band across the corner of the 
rectangle. Diagonals joining the corners of this figure are inclined at an angle of 45° 
to the cotyledonary plane. 
This position is the peculiarity of the Sapotacez and is known in few instances outside 
the order. It is maintained throughout the transition from root to hypocotyl and from 
hypocotyl to cotyledons (Pl. 25. figs. 2-8, Pl. 26. fig. 9). It constitutes an exception to 
the rule enunciated by Dangeard *:—* Le plan vertical médian des cotylédons correspond 
toujours à un faisceau vasculaire de la racine." Throughout her seedling research 
Miss Thomas t has found Dangeard's rule to hold good, except in the case of Fagus 
and Quercus. Nowhere do I find any other exception vouched for. 
A seedling measuring 95 mm. from root-apex to cotyledonary node shows two large, 
expanded, epigeal cotyledons, sessile, and with the shoot between them still only repre- 
sented by a cone of meristemmatic tissue (fig. 1). The lower 40 mm. of the root are of 
nearly uniform diameter. Above this the axis widens suddenly, maintains its increased 
girth for about 20 mm., and then resumes that of the lower portions. A transverse 
section of the root 13 mm. from the apex (82 mm. from the node) shows it to be tetrarch 
with a large pith (fig. 2). Each xylem group consists of a single radial file of elements, 
the smallest external. A little higher the radial file is double and soon the internal parts 
* Loc. cit. p. 87 (cf. post, p. 199). t Loc. cit. p. 77 (cf. post, p. 199). 
