100 YEARS AGO

The issue of the Revue Scientifique (Revue Rose) of March 9 contains a long and interesting article by M. Louis-Adrien Levat on the destruction of birds, especially by means of traps and snares, which he declares to be illicit . . . during a single spring a few years ago no less than 1500 nests were taken in one French province. This represents a prospective loss of about 6000 birds, which might be expected to consume some 6,000,000 insects among them. He adds the significant observation that in the year 1860 one hundred cages filled with insectivorous birds of various kinds were exported from Baden to New South Wales; and that at the present day it would be almost impossible to send such another cargo, owing to the scarcity of these birds on the continent. And it is not alone the disappearance of bird-life and bird-song from the country districts that is to be deplored. The effects on agriculture, horticulture and the grape industry are simply disastrous. Some birds, it is computed, will consume 200,000 insects per season, and others as many as 600 per day. . . In Hérault alone the destruction of insectivorous birds is calculated to cost the department 100,000 hectolitres of wine annually.

From Nature 21 March 1901.

50 YEARS AGO

The 'membrane', that is, the electric double layer, surrounding the muscle fibre generates no field of forces inside the system. If, however, part of the membrane becomes depolarized, the depolarized part acts . . . as a 'window' in the closed system and an electric field is generated. If the depolarization should occur with a sharp border, the maximal intensity of the field in the axis of the fibre would correspond to a field generated between the two plates of a condenser placed at a distance equal to the diameter of the fibre and having the same potential difference as the two sides of the 'membrane'. If the wave of depolarization travels along the membrane, electrodes along the axis charged correspondingly. Experiments, performed along this line by St. Hajdu and one of us, show that such a field will actually bring the contractile matter directly to contraction even if the membrane is inoperative. . . There seems to be thus no 'transmission' of excitation from the membrane to the contractile matter; depolarization and the elicitation of contraction merge into one single physical event.

From Nature 24 March 1951.