Scott and Mas ten. — The Structure of Trigonocarpus. in 
attachment, as in Lepidocarpon , and, according to Prof. Oliver, probably in 
Stephanospermum 1 , or whether the relations were as in the modern Cycads, 
and in Lagenostoma , in which the testa and nucellus are adherent excepting 
right at the top of the seed- A discussion of this question will best be 
deferred until after the structure of the nucellus has been described, but 
here we may say that in Trigonocarpus as in Stephanospermum, the evidence 
supports the view that the nucellus was free. 
The Chalazal End of the Seed. 
An account may now be given of some of the details of the structure of 
the lower part of the seed. Some of the longitudinal sections afford evidence 
that the seed was attached to the parent plant by means of a stalk. The 
stalk is shown in PL XII, Fig. 12. As shown in the figure, the sarcotesta 
of the stalk of this specimen has undergone considerable displacement and 
compression as is made evident by the crushed tissue on the right-hand side 
of the stalk and the repetition of the limiting tissues of the sarcotesta on the 
other. The form of the stalk shown in this section is therefore not the 
natural one, nor is the unsymmetrical position of the stalk with reference 
to the chalazal attachment above. Other sections show the stalk sym- 
metrically placed. As shown in PI. XII, Fig. 12, as well as in some other 
slides, the stalk appears to consist almost entirely of parenchymatous tissue 
continuous with the inner, denser, zone of the sarcotesta, but this appearance 
is really due to the fact that the section passes somewhat tangentially, not 
medianly, through the base of the seed, although, as it passes through the 
chalazal attachment of the nucellus it cannot be very far from the median 
plane. Apparently the median plane of the stalk is more closely approached 
right at the bottom of this section, as here it passes into sclerotic tissue, t., 
which is probably part of the central core of the stalk continuous with the 
sclerotesta of the body of the seed. 
Many of the more nearly median longitudinal sections show the central 
core of sclerotic tissue of the stalk in the form of a downwardly directed 
pointed prolongation of the sclerotesta, the shortness of which, in most 
of the slides, is doubtless due to the slight obliquity of the sections. In one 
section the sclerotic stalk has a length of about 1-5 mm., and in another 
slide it is traversed longitudinally by the main supply bundle of the seed. 
The sclerotic tissue of the stalk probably gradually died out below, the hard 
core becoming smaller as its tissue was replaced by the thinner-walled cells 
of the sarcotesta. We have already seen that in this part of the seed the 
passage from sclerotesta to sarcotesta is a gradual one. Judging from 
the longitudinal section shown in PI. XII, Fig. 12, the sclerotic axis of the 
stalk must have had a length of more than 4 mm., as the sclerotic tissue, j*. t., 
1 Oliver (’04) (1), p. 368. 
