Abstract
Der Naturforscher, October 1875.—In this number is given an observation by M. Coulier, that while a cloud was formed in a vessel containing a little water, when an attached caoutchouc balloon was first compressed, then allowed to expand, no cloud was thus produced if the vessel had stood some time at rest, or if the air had been filtered; and the author's view was confirmed that small particles in the air were what caused the formation. M. Mascart has found that strongly ozonised air is not robbed of its cloud-forming action by filtering.—There are two valuable papers in meteorology, one by M. Hann, on the variability of daily temperature, and another in which M. Kerner offers an explanation of the fact that there is, in the Swiss valleys, in late autumn and winter, a middle warm region limited both below and above by a colder.—In physiology we note some interesting researches by M. Bernstein as to what is the highest pitch of tone a muscle may be made to give by electric stimulation. Above 418 vibrations per second of the spring contact, the muscle tone (the same as that of the spring) was distinct, though weaker; at 1,056 vibrations no distinct tone was observed, only a noise. But if the nerve were stimulated to the latter degree the muscle gave a tone, not indeed the same as the spring, but a fifth, sometimes an octave, lower. The upper limit beyond which the muscle ceased to give the same tone with the spring (in this arrangement) seemed to be about 933 vibrations. Under chemical stimulus of a nerve, the connected muscle gave a tone like that in natural contraction.—There is also a suggestive paper by M. Delboeuf on the theory of sensation, and M. Hirschberg describes observations on a boy who acquired sight at seven years of age; they favour, he considers, the empiristic theory of sight-perceptions.—In a paper on the origin of the deep-water fauna of the Lake of Geneva, M. Forel thinks the entire fauna of the Swiss lakes are descended from forms which have migrated (up the rivers) since the melting of the glaciers, and have afterwards been differentiated.
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Scientific Serials . Nature 13, 97–98 (1875). https://doi.org/10.1038/013097a0
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DOI: https://doi.org/10.1038/013097a0