ZOOLOGY AND BOTANY* * * § MICROSCOPY* ETC. 
55 
the stream. Nine species were indifferent ; none negatively rheotropic. 
The curvature appeared to be a response to irritation. 
(4) Chemical Changes (including 1 Respiration and Fermentation). 
Physiology and Biology of Winter-Green Plants.* — Understanding 
by “ winter-green ” plants not only evergreen perennials, but also such 
biennial or annual herbaceous plants as maintain the activity of their 
leaves in the winter, e.g. Senecio vulgaris , Geranium robertianum , Dr. B. 
Lidforss states that they are characterised by the entire absence of 
starch from the guard-cells of the stomates during the cold season ; it 
has already completely disappeared by December ; but its formation is 
at once induced by a higher temperature. The same is true of the 
mesophyll-cells of the leaf. These contain, on the other hand, large 
quantities of a soluble carbohydrate, probably glucose ; and the author 
regards the transformation of starch into glucose as a protection against 
cold, similar to the formation of oil in many trees. Submerged plants, 
mosses, and green algae exhibit similar phenomena. 
y. General. 
Divergence of Monocotyledons and Dicotyledons.! — Prof. C. E. 
Bessey points out that Monocotyledons and Dicotyledons cannot have 
diverged from one another at what are generally regarded as the lowest 
members of each group, viz. the Typhaceae, Pandanaceae, Naiadaceae, &e. 
on the one hand, and the Piperaceae, Chloranthaceae, Salicaceae on the 
other hand ; since these orders show no kind of affinity with one another. 
He considers, on the other hand, that external anatomy, histology, and 
embryology point to a genetic relationship between the apocarpous 
Monocotyledons (AlismaceaB, Naiadaceae, &c.) on the one hand, and the 
Thalamifloral Ranales (Ranunculacese, Magnoliaceae, Nymphaeaceae, &c.) 
on the other hand. 
Graft-Hybrid.^ — Prof. N. Wille records a remarkable instance of 
apparent graft-hybridism of a pear on a whitethorn. The fruits are 
small, pear-shaped, with the colour of the fruit of Crataegus, 5-celled, 
but usually sterile ; the leaves have all the appearance of pear-leaves. 
Fossil Plants of the Coal-Measures.§ — Parts 2 and 3 of this important 
work, by the late Prof. W. C. Williamson and Dr. D. H. Scott, comprise 
the detailed account of their researches on the roots of Calamites and 
on Lyginodendron and Heterangium , which appear to belong to a fossil 
group on the border-land of Ferns and Cycadete. 
B. CRYPTO GAMIA. 
Cryptogamia Vascularia. 
Female Prothallium of the Heterosporous Lycopodiaceae.[| — From 
observations on the germination of the megaspores of Isoetes malinverniana 
* Bot. Centralbl., lxviii. (1896) pp. 33-44. 
f Bot. Gazette, xxii. (1896) pp. 229-32. 
X Mitt. Biol. Gesell. Christiania. See Biol. Centralbl., xvi. (1896) p. 126. 
§ Phil. Trans. R. S., clxxxvi. (1896) pp. 683-779 (15 pis.). Cf. this Journal, 
1895, pp. 338, 660. || Bot. Ztg., liv. (1896) l ta Abt., pp. 159-68 (1 pi.). 
