590 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Herr C. Verlioeff * describes the adaptation of tbe flower for cross- 
pollination, and of the visiting insects, in 75 species of flowering plants 
growing in the island of Norderney* 
Germination of Pollen-grains. | — Prof. J. E. Green has made a 
series of observations on the germination of the pollen-grain and the 
nutrition of the pollen-tube in a large number of plants belonging to 
many different natural orders. He finds in the pollen-grain either one 
or both of two different enzymes, diastase and invertase ; these may be 
extracted by the same treatment as has been found effectual in the cases 
of seeds and foliage-leaves ; the quantity is largest at the period of 
commencement of germination. The pollen-tube is nourished during 
its growth by plastic reserve-material derived either from the grain 
itself or from a secondary store deposited in the style. This consists 
in different species of different carbohydrates — starch, dextrin, cane- 
sugar, maltose, and glucose ; but dextrin is not found in the style. The 
style contains a further quantity of enzymes, and the pollen-tube itself 
excretes the same ferments during its progress down the conducting 
tissue of the style. 
The absorption of food-material appears to be one cause of the 
increase of enzyme which takes place during germination ; and this 
absorption is usually so active that the reserve-store of the pollen-grain 
is often largely increased by a temporary deposit, either in the grain or 
tube, of some of the absorbed sugar in the form of starch. 
(2) Nutrition and Growth (including- Germination, and Movements of 
Fluids). 
Influence of Light on the Germination of Seeds.j; — Contrary to 
the statement of some previous observers, Herr B. Jonsson asserts, as 
the result of observations on a large number of plants, that light greatly 
promotes the germination of seeds, and that the favourable influence is 
not in any way due to the rays of heat. Seeds of different species vary 
very greatly in their sensitiveness to light. 
Action of Magnetism on Germination.§ — Sig. G. Tolomei finds, as 
the result of a series of experiments (on Phaseolus vulgaris'), that a 
magnetic field of feeble intensity has no appreciable effect on the 
germination of seeds ; while a field of greater intensity causes a more 
or less increased rapidity of growth, in proportion to the proximity of 
the growing plant to the point of greatest magnetic intensity. Young 
plants are diamagnetic. 
Work and Pressure in Growing Plants. |] — Prof. W. Pfeffer has 
undertaken a series of experiments for the purpose of determining the 
relations between the energy of the work performed by plants and the 
pressure exercised upon the organism by external and internal forces. 
The structures on which the experiments were made were roots and 
stems, chiefly of Zea Mays , Vida sativa, and V. Faba, the nodes of 
* Nov. Acta K. Leopold-Carol. Deutsch. Akad. Wiss., lxi. (1S93) 3 pis. and 
numerous figs. See Bot. Centralbl., lviii. (1894) p. 178. 
f Proc. Roy. Soc., lv. (1894) pp. 124-7; Ann. Bot., viii. (1894) pp. 225-8. 
X Acta Univ. Lund., xxix. (1893) 47 pp. See Bot. Centralbl., lviii. (1894) p. 398. 
§ Malpighia, vii. (1894) pp. 470-82. 
|| Abhandl. K. Sachs. Gesell. Wiss., xx. (1893) pp. 235-474 (14 figs.). 
