ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
329 
Dr. Ida A . Keller * brings forward some observations tending to 
show that self-pollination not unfrequently occurs in flowers which are 
apparently adapted for cross-pollination, and emphasises the danger of 
drawing hasty conclusions as to the importance of insects in promoting 
cross-pollination . 
(2) Nutrition and Growth (including- Germination, and Movements 
of Fluids). 
Physiology of Drosophyllum.t — M. A. Dewevre describes the ana- 
tomical structure of Drosophyllum lusitanicum , a member of the 
Droseracese which differs from the rest of the order in being an inhabi- 
tant of dry situations. The most important special point of structure 
noted is that the ultimate branches of the vascular bundles which proceed 
towards the leaf-glands are destitute of sieve-tubes. The heads of the 
leaf-glands are covered by an uninterrupted cuticle, through which 
there is an abundant excretion of mucilage. This mucilage is not of 
a proteid character, but belongs to the cellulose group ; it contains 
neither nitrates, phosphates, potassium, nor sugar ; but calcium, sodium, 
and an organic acid, which is certainly not formic. The mucilage has 
the power of dissolving fibrin, legumin, and albumin, a property which 
cannot be attributed to bacteria contained in it ; no diastatic ferment 
could be detected in it. Contrary to the statements of Darwin and 
Goebel, the author was quite unable to establish any absorption of the 
digested substances into the tissue of the leaf. The glands and their 
secretion seem to act simply as a protection to prevent the access of 
injurious fungus-spores and bacteria to the loose tissue of the leaf. 
Physiology of Hoot-Tubercles of Alnus glutinosa.J — Herr L. Hiltner 
cultivated two tuberculated and several non-tuberculated alders in quartz- 
sand devoid of nitrogen and mixed with suitable nutrient material. In 
the course of a few weeks a comparison showed differences greatly in 
favour of the plants having root-tubercles. The non-tuberculated plants 
evinced a strong growth only after the formation of root-tubercles for 
which they were inoculated. Alders were also cultivated in nutrient 
solution, and the cultures successfully inoculated with rubbed-up nodules. 
After the tubercles had attained a certain size, two of the plants were 
deposited in nutrient solution quite devoid of nitrogen, two others being 
placed in normal nutrient solution. While the tubercles on the latter 
scarcely grew at all, though the plants, owing to the presence of nitrogen 
in the medium, did well, the nodules in the non-azotised medium greatly 
increased in size, attaining a diameter of 8 mm. These latter, kept for 
two years in non-azotised medium, had stems 10-20 mm. in diameter, 
thirty branches, and from 300-500 leaves. From these experiments the 
author infers that alders, in virtue of their root-tubercles, possess the 
power of collecting nitrogen, a power of which the nodule-free plant is 
devoid. In soil rich in nitrogen, the action of the root-tubercle is 
unimportant or even absent. It seems probable that the effective 
organism finds its way in through the root-hairs. 
* Ann. and Mag. Nat. Hist., xvii. (1896) pp. 249-55. See also Proc. Acad. Nat. 
Sci. Philadelphia, 1895, pp. 555-61. f Ann. Sci. Nat. (Bot.), i. (1895) pp. 19-66. 
X Landw. Vers.-Stat., xlvi. (1895) pp. 153-61 (1 pi.). See Central bl. f. Bak- 
teriol. u. Parasitenk., 2 te Abt., ii. (1896) pp. 97-8. 
