ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
817 
Seed-coats of Euphorbia.* * * § — Mr. L. H. Pammel describes the structure 
of the seed-coats in those species of Euphorbia which are natives of the 
United States. He finds that, from a systematic point of view, they 
offer but few characters of sufficient importance to use in distinguishing 
species. Where the outer suface of the seed shows sculpturing or 
marking, the minute structure indicates corresponding differences; the 
ashy part which covers many seeds is changed into mucilage on the 
addition of water, and in the case of E. polygonifolia, spirals are 
developed. Microchemically this mucilaginous substance appears to be 
similar to the mucilage of Linum , Buellia, Ocymum , Salvia , &c. Under- 
lying the mucilaginous layer is a narrow zone in which starch-grains 
are abundant. 
Epiderm of the Seeds of Cuphea.f — Herr C. Correns describes the 
mechanism which causes the sudden appearance of a felt of hairs on 
the epiderm of the seeds of various species of Lythraceae — Lythrum 
thesioides, Peplis , Ammansia verticillata , and especially Cuphea viscosis- 
sima — when wetted. From the inner side of the outer wall of each 
epidermal cell springs a coiled hair of nearly uniform thickness, which 
almost completely fills up the cell-cavity. The inner lamella of the 
cell- wall and the membrane of the hair give the reactions of cork. 
When moistened the outer wall of the epidermal cell still remains attached 
to one side like an open lid. The hair gradually uncoils, still clothed 
with a membrane, which is the inner lamella of the cell-wall. The 
remains of the protoplasm of the cell are at the same time expelled. 
The unfolding of the hair is not due to vital activity, since it takes 
place in preparations that have lain for some days in alcohol. It is a 
purely physical phenomenon, a process of swelling. 
Tendrils of Passiflora.J — Mr. D. T. M‘Dougal describes in detail 
the morphology and anatomy of the tendrils of Passijlora cserulea , which 
consist of three distinct parts, — the base or non-coiling portion, the 
middle region or coiling portion, comprising the greater part of the 
organ, which is generally slightly curved, and the sharply curved or 
hooked tip. Near the extremity of the concave side of the tip is the 
oval aperture of the cup-formation. The whole organ shows a bilateral 
structure. All the tissues of the tendril are abundantly supplied with 
pits. The author believes that the concentration of the protoplasm in 
the epidermal layer has a direct connection with the irritability of the 
tendril, and that its movements are due to changes in the chlorophyll 
layer, the disposition of the xylem elements being favourable to rapid 
flexion and extension ; the abundant supply of reserve food-material 
seems to be a provision for the rapid growth and fixation of the tendril 
upon coiling. 
Comparative Anatomy of Cotyledons.§ — Herr H. Klotz has ex- 
amined the structure of the cotyledons in a number of plants belonging 
* Trans. Acad. Sci. St. Louis, v. (1892) pp. 543-68 (2 pis.). Cf. this Journal, 
ante , p. 504. 
f Ber. Deutsch. Bot. Gesell., x. (1892) pp. 143-52 (1 pi.). 
t Bot. Gazette, xvii. (1892) pp. 205-12 (1 pi.). 
§ ‘EinBeitrag z. vergleich. Anat. d. Keimblatter,’ Halle, 1892, 67 pp. See 
Bot. Centralbl., 1892, Beih., p. 260. 
