Scott and M'aslen . — The Structure of Trigonocarpus. 103 
view of the strong probability, on other grounds, of a relationship between 
Meduilosa and Trigonocarpus , it is not impossible that a small-celled 
epidermis may be subsequently discovered in the former genus. In the 
meantime, the apparent absence of this layer in Meduilosa renders Wild’s 
comparison less close than he thought. 
As already briefly described, the outer series of vascular bundles of 
the seed traverse the sarcotesta and they are occasionally seen in transverse 
sections of the seed, although, owing to the usual non-preservation of 
anything more than a few layers of the inner sarcotesta, such sections 
are quite rare. The bundles spring from the main supply-strand at a 
considerable distance below the chalaza, and bending outwards traverse 
the sarcotesta of the body of the seed, running opposite to the secondary 
ridges of the sclerotesta. The position of one of the sarcotestal bundles 
is indicated at s. b . in PI. XI, Fig. 5. The bundle itself cannot be dis- 
tinguished in this photograph, but is shown more highly magnified in 
PI. XIV, Fig. 28. Traces of sarcotestal bundles can be seen in other slides, 
and in all cases they appear opposite to the secondary, never to the 
principal, ridges of the sclerotesta. The total number of sarcotestal 
bundles would thus have been nine, or perhaps only six, in ordinary 
specimens, such as that shown in PI. XI, Fig. 5. It seems probable 
that the number was really six. In no single section are sarcotestal 
bundles seen opposite to all the secondary ridges of the sclerotesta, and 
in all the sections in which the bundles are visible, they appear invariably 
opposite to the two outer of each set of three secondary ridges, never 
to the central one. The central secondary ridge frequently differs from 
the lateral ones in being more rounded, and, moreover, as we shall see later, 
it is the first ridge to disappear when traced up to the upper end of the 
seed. It seems probable that it also differs in having no sarcotestal bundle 
opposite to it. That there are six, not nine, sarcotestal bundles is also 
favoured by examination of the section across the base of the seed shown 
in PI. XI, Fig. 3. This is an approximately transverse section cut some 
distance below the chalaza ; careful examination of the original section 
shows six bundles, £., embedded in the compact sarcotesta, and doubtless 
these are the same bundles that afterwards appear opposite to some of 
the secondary ridges of the sclerotesta in the body of the seed. The 
central mass of sclerotic tissue which is seen in this section (PI. XI, Fig. 3, 
s. t.) is produced on one side into a projection, which in all probability 
represents the lower end of one of the principal longitudinal ridges of 
the sclerotesta, cut through owing to slight obliquity of the plane of section. 
No sarcotestal bundle can be seen opposite to this ridge, although two 
occur symmetrically disposed on either side of it, so that this section helps 
to confirm the conclusion as to the number and position of the bundles 
arrived at above. 
