384 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tion that the vascular bundles of the stem are bicollateral. Besides the 
normally developed leptome there are formed in the pith several 
leptome-bundles which arise in the medullary parenchyme quite inde- 
pendently of the outer leptome. 
C4) Structure of Organs. 
Morphology of the Carpel.* — Sig. F. Pasquale proposes a new 
theory of the morphology of the carpel, founded on an extended observa- 
tion of the course of the vascular bundles, chiefly in the Sterculiace®, 
Leguminos®, and Crucifer*. Instead of being, according to the preva- 
lent view, a single modified leaf, the carpel is, according to him, the 
result of the concrescence of three, less often of two, leaves, which take 
part in the formation and in the nutrition of the ovules and of the seeds. 
He terms it, therefore, a triphyllome, of which one leaf is sterile, and has 
an inferior position, the other two are superior and fertile. Between 
the fertile and the sterile leaves there is an actual and intimate fusion, 
with perfect anastomosis of the ultimate ramifications of the vascular 
bundles, and even of the mesophyll and the epiderm. Each fertile leaf 
is composed of a membranous portion with a system of vascular bundles, 
the placental hemiphyll, and of an ovular hemiphyll, which is entirely 
transformed into the placental body and the ovules ; by the placental 
body is understood the whole of the tissues which constitute the placenta, 
together with the funicles, the style, and the stigma. The sterile leaf, 
represented by the dorsal portion of the consolidated carpellary leaf, is 
frequently reduced to a single principal bundle with a few lateral 
bundles ; sometimes it is altogether wanting. The fertile leaves unite 
with one another by their respective mid-ribs. Each fertile leaf is com- 
posed of a membranous hemiphyll, which takes part in the formation of 
the pericarp or of the septum, and of a hemiphyll folded in the cavity 
of the carpel, and transformed into a placental body. The ovules 
originate from the whole of the ovular hemiphyll, and not merely from 
the carpellary teeth or margins. In many monocarpellary pistils, such 
as those of Gramineae, Composite, and Leguminos®, two stigmas are 
present, owing to their origin from two fertile leaves. The false septum 
of Crucifer® is an emergence of the ovular hemiphylls. 
Fruit of the Bay.f — Sig. F. Neri describes the fruit of Laurus 
nobilis, which with Luerssen he is inclined to call drupaceous. The 
epicarp adheres closely to the soft mesocarp, and the endocarp clings to 
the seed. The single layer of epidermal cells forming the epicarp and 
the lenticels which replace some of the stomates ; the hypodermal part 
of the mesocarp consisting of two or three layers of flattened cells with 
dense pigmented protoplasm, and the thicker internal portion with oil- 
cells ; the thin endocarp, the seed, and the embryo, are all described. 
Ovule and Seed of Trapa.f — Dri. G. Gibelli and F. Ferrero have 
made a careful study of the structure of the ovary and ovule, the mode 
of impregnation, and the structure and development of the ovule, in 
Trapa natans, which bring them to the conclusion that it presents 
* Bull. Soc. Bot. Ital., i. (1892) pp. 26-36. 
t Atti Soc. Tosc. Sci. Nnt., vii. (1891) pp. 309-14, 
J Malpighia, v. (1891) pp. 156-218 (10 pis.). 
