ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
209 
asper and oleraceus , Mercurialis annua , Chenopodium album , j Ualsamina 
hortensis , Impatiens glandulifera , and Scrophularia aquatica. 
Thorns of Randia dumetorum.* — Mr. P. Groom discusses the 
nature of the remarkable thorns of this plant, belonging to the RubiaceaB, 
and decides that they are accessory branches. They may develope into 
a shoot and bear leaves; they arise and grow like a shoot; and their 
structure agrees with that of a shoot. Their function appears to be the 
defence of the young branches. 
Root-tubercles of Elseagnus and of the Leguminosse.f — As the 
results of a series of experiments made on Elseagnus angustifolius , 
Herren F. Nobbe, E. Schmidt, G. Hiltner, and E. Hotter state that 
seedlings infected with the microbe which produces the root-tubercles 
are in all cases more vigorous than those which are not infected. The 
symbiotic microbe is not, however, Bacterium radicicola , but a totally 
different organism. 
In the case of Leguminosae, when the root-system is normally de- 
veloped, the formation of the tubercles is not dependent on the age of 
the plant ; but young root-fibres can be infected only so long as they 
still possess root-hairs. 
0. Physiology. 
Cl) Reproduction and Embryology. 
Cross- and Self-pollination-! — Mr. T. Meehan records the following 
notes on the mode of pollination of American plants : — Euphrasia offici- 
nalis presents, as Darwin has stated, an arrangement for ensuring 
self-pollination, notwithstanding its well-marked proterogyny. Gaura 
parviftora (Onagraceae), which flowers at night, is absolutely self-polli- 
nated, while G. biennis appears to be chiefly pollinated by night-flying 
moths. (Enothera biennis is apparently self-pollinated. In Bhus copal - 
lina the female flowers exude great abundance of a sweet liquid which 
attracts insects in large numbers; while the male flowers have very 
conspicuous golden pollen and no honey-glands; no insects were seen 
to pass from one to the other. In Dalibarda repens the female flowers 
are cleistogamous and self-pollinated. Lysimachia atropurpurea is self- 
fertile, but probably occasionally self-pollinated. Campanula rotundi- 
folia produces seeds when insect-visitors are excluded. In Trifolium 
hybridum the abundant fertility is due to self-pollination. Lathyrus 
maritimus appears to be absolutely self-fertile. In JRaphanus sativus 
some plants seem to be arranged for cross-, others for self-pollination. 
A series of experiments carried out by Miss M. Reed § fully confirm 
Darwin’s statement that cross-fertilized produce more seed-vessels than 
self-fertilized plants, and that the capsules are heavier. The experiments 
were made on Petunias. 
Pollination of Yucca.||— Prof. C. Y. Riley gives the results of 
observations carried on through a long series of years, "of the pollina- 
* Ann. Bot., vi. (1892) pp. 375-9 (4 figs.). 
t Landwirthsch. Versuchsstat,., xli. (1892) pp. 137-40. See Bot. Centralbl., lii. 
(1892) p. 379. Cf. this Journal, 1892, p. 234. 
X Proc. Acad. Nat. Sci. Philadelphia, 1892, pp. 366-83. 
§ Bot. Gazette, xvii. (1892) p. 330. 
|| Ann. Rep. Missouri Bot. Garden, 1892, pp. 99-158 (10 pis) See Bot 
Centralbl , lii. (1892) P . 267. 
