THE POPULAR SCIENCE MONTHLY.
Mechanism of Thought.—An important paper was read at the last meeting of the Medico-Chirurgical Society of London on this interesting but very complicated subject, by Dr. Broadbent. His theory was based partly on the results of his own dissections, partly on remarkable cases of loss of speech and paralysis that either came under his own notice or have been recorded by others. The chain of physical actions which he claims to be implicated in the process of thinking, can only be followed in detail by the anatomist; but the general sequence of events on this theory is: the formation of ideas in the marginal convolutions at the summit of the sensory tract; the employment of these in trains of thought in the convolutions withdrawn from immediate relation with the outer world; the propagation of excitations to the third left frontal convolution, leading to the selection of certain sound-groups; the coördination in the corpus striatum of the muscular movements required to produce those sounds; and, finally, the transmission of impulses from the several nuclei of the medulla oblongata to each individual muscle required to be brought into play.—Academy.
Aërial Navigation.—Dupuy de Lome gives a brief account of an aerial journey made by the author in company with fourteen others in a newly-constructed air-balloon, and machinery for imparting to this balloon and the car thereto attached any desired direction or motion, independent of that which the wind or air-currents will give to the balloon. The experiment has proved a complete success in every respect; a speed of 50 kilometres (31.065 English miles) per hour could be readily obtained.
Prof. Ehrenberg, who has published from time to time the results of his examination of those microscopic bodies that are carried by the atmosphere and deposited as substances of a red color, has collected all the observations on this subject made by him between the years 1847 and 1870. This important memoir, consisting of 150 pages, two tables, and two plates, will appear in the forthcoming volume of the Transactions of the Berlin Academy for 1871. He enumerates all the instances of this phenomenon which have been placed on record; the earliest being a case of dust-shower which fell for ten days in the Chinese province Honan, in the year 1154 b. c. As his examination was directed chiefly to organisms contained in the showers, the analysis was entirely microscopical, not chemical. The number of analyses made by himself is altogether 70, and he was able to distinguish not less than 460 distinct forms of organic life.—Academy.
If there were any reasonable question of the value of vaccination as a preventive of small-pox, strong evidence in its support is furnished by the circumstance of an epidemic now prevailing in the Island of Jersey. It appears that, of 39 persons comprising all who were attacked with small-pox in the small town of Gorey, but five had ever been vaccinated. Six of the 39 died, and but one of these had ever been vaccinated. At last accounts, the epidemic was rapidly spreading, and under very favorable conditions it would seem, for investigation has shown that at least one-third of the children under 15 years of age in the whole island are unvaccinated.
Nitrate of Ammonia in Respriration.—Dr. Struve states that, by breathing for some moments in a large-sized beaker-glass previously moistened with water, and next rinsing the glass with some pure distilled water, this liquid will be found, by the usual tests, to contain ammonia and nitric acid. This formation of nitrate of ammonia is stated to become increased after dinner has been taken. The author is of opinion that atmospheric nitrogen is not entirely passive in the process of respiration, but it should be observed that this opinion is contradicted by the direct experiments of Drs. Regnault and Reiset.—Chemical News.
Dr. Livingstone's safety is not yet despaired of by his brother, Mr. Charles Livingstone, her Majesty's consul at Fernando Po. This gentleman is no stranger to Africa, having been long resident of the west coast, and travelled much about that portion of the continent. He is stated to be confident that the doctor will, in the course of a few months, reach the seaboard at or near Zanzibar, and to hold the fact of the opening up of a new river on the west coast, between Opobo and New Calabar, to be a proof that Africa, even there, is only imperfectly known.—Lancet.
Since attention has been directed to the subject, cases of lead-poisoning, traceable to the use of hair-preparations containing lead, are found to be very frequent. A case of this sort was recently reported in the medical journals, which was at first mistaken for muscular rheumatism, and treated as such, with but slight amendment. Paralysis of the extensor muscles of the fingers and hands, with "wrist-drop" coming on, the true nature of the affection was seen, and its cause readily found in the frequent use of a hair-renewer containing a large proportion of sugar of lead. No lines were seen upon the gums, but attacks of colic had been frequent. Discontinuance of the hair-dressing, and a resort to the ordinary remedies, soon effected a cure.