492 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Amaryllideae, and a large portion of the Liliacete ; the second, though 
regarded as exceptional, is found in certain genera belonging to a large 
number of different natural orders ; the third, in genera of Lythraceae, 
CEnothereae, Magnoliaceae, and Aristolochiaceae. In the greater part of 
the Gamopetabe and Apetalae, as well as in some Apopetalae, the ovules 
aro provided with only a single integument, and the envelopes of the 
seed are either developed from this integument alone, or the nucellus 
partakes in its formation. The latter case occurs in species belonging 
to the Linaceae, Rhamnaceae, and Compositae. In most cases the inner 
layers of the integument of the ovule disappear in the course of develop- 
ment of the seed. 
In opposition, therefore, to the view usually entertained, the author 
asserts that in those plants in which the ovule has a double integument, 
the inner envelope does not, as a rule, disappear in the course of 
development of the seed, but persists, and often constitutes the lignified 
portion of the seminal integument* The nucellus itself sometimes 
contributes to the formation of the mature envelope ; and it is only in 
a few families that this is formed entirely from the outer integument of 
the ovule. In those plants in which the ovule has only a single envelope 
the lignified portion of the seminal integument has its origin, in some 
cases, in the epiderm of the nucellus. 
Integuments of the Seed of Cruciferae.* — M. J. d'xYrbaumont has 
arrived at the following conclusions respecting the seminal integuments 
of the Geraniaceae, Lythraceae, and CEnothereae: — (1) The two integu- 
ments of the ovule frequently remain in the ripe seed. (2) The nucellus 
frequently contributes to the formation of the seminal integuments. 
(3) The endosperm itself even takes part in this format' on. The object 
of the present paper is to show that this last often takes place also in 
the Cruciferae, and especially in Brassica nigra and Sinapis alba. A 
layer formed from the endosperm is also present in Iberis pinnata, 
Conringia perfoliata , Biscutella ambigua , Cochlearia officinalis , &c. ; 
sometimes this layer is reduced to a thin lamellated pellicle, as in 
Capsella bursa-pastoris, Camelina sijlvestris , Thlaspi perfoliatum , Hesperis 
matrcmalis , &c. 
Stem of Zostera.f — M. C. Sauvageau has studied the structure of the 
stem in the five species of Zostera — Z. marina , Capricorni, nana, Mueller i, 
and tasmanica , Z. marina being taken as the type. The cortical paren- 
chyme is composed of a close external and an internal zone containing 
lacunae ; in the internal zone are fibrous strands, which are either in 
contact with the epiderm, or are separate, and, in one of the species 
(Z. Muelleri), surround the central cylinder. There are always cortical 
foliar bundles, either one on each side ( Z . marina , Capricorni , and nana), 
or two to five (. Z . Muelleri and tasmanica ). The central cylinder is always 
surrounded by an endoderm, the phloem-bundles are more frequently 
isolated and distinct, while the xylem-bundles are united. A knowledge 
of the structure of the stem greatly facilitates specific determination. 
* Bull. Soc. Bot. France, xxxvii. (1890) pp. 251-7. Cf. this Journal, 1890, 
p. 737. 
t Journ. de Bot. (Morot), v. (1891) pp. 33-45, 59-68 (9 figs.). Cf. this Journal, 
1890, p. 741. 
