Page:Popular Science Monthly Volume 10.djvu/778

758 place sufficiently long to prove that the urine had been perfectly sterilized by the boiling. The flasks were then rudely shaken, so us to break the capillary ends of the potash-tubes and permit the liquor potassæ to mingle with the slightly acid liquid. The urine thus neutralized was subsequently exposed to a constant temperature of 122° Fahr., which is pronounced by Dr. Bastian to be specially potent as regards the generation of organisms.

Ten flasks, prepared as above described toward the end of last September, remained perfectly sterile for more than two months. There is no doubt that they would have remained so indefinitely.

Three retorts, moreover, similar to those employed by Dr. Bastian, and provided with potash-tubes, had fresh urine boiled in them on the 29th of September, the retorts being sealed during ebullition. Several days subsequently, the potash-tubes were broken, and the urine neutralized. Subjected for more than two months to a temperature of 122° Fahr., they failed to show any signs of life.

The Phenomena of Hypnotism.—Dr. Heubel, in Pflüger's Archiv, rejects Czermak's explanation of hypnotism (see vol. iii., p. 618, vol. iv., p. 75), as also the explanation offered by Kircher and Preyer, and thinks that all previous investigators of this phenomenon have witnessed only its first stage—that which is most easily induced in animals of relatively high organization. Cold-blooded vertebrates, such as the frog, may be reduced to a state of complete immobility at will; they will remain in a constrained position for hours, instead of seconds or minutes. This abolition of voluntary movement and of consciousness is, according to the author, nothing but ordinary sleep. He holds that the waking state requires for its maintenance a continual stimulation of the higher nervous centres by impressions conveyed to them along the various centripetal nerve-fibres. By forcing an animal to remain motionless for a brief interval (without inflicting pain), and simultaneously excluding visual and auditory sensations from its brain, we suddenly deprive its nerve-centres of a large proportion of their accustomed stimuli. Accordingly, they are unable to remain awake, and their functional activity is only restored to them when they are roused by some impulse from without. Having satisfied himself in a variety of ways of the correctness of this explanation as applied to the phenomena exhibited by the frog, Heubel proceeds to extend his results to birds and mammals, and arrives at the conclusion that "forced sleep" will account for all the facts hitherto observed.

Further Experiments with Putrescible Fluids.—Mr. Dallinger has communicated to the Royal Microscopical Society of London some further results of his experiments with sterile putrescible fluids. In these experiments, an air-chamber after Tyndall's plan was used, and it was tested for motes by a beam of oxyhydrogen-light. The germs were obtained from a maceration of haddock's head that had been kept for fifteen months, and found to contain numbers of the "springing and calycine monads" of former papers, many of them in a condition for emitting spores. A portion of this material was evaporated at the temperature of 150°. Dust from it was diffused through the Tyndall chamber, and, after the heavier particles had settled, in the course of four and a half hours, ten small glass basins filled with Cohn's nutritive fluid, freshly prepared, were introduced, six being open and four covered with glass lids. In this condition they were left for twenty-four hours, and then the lids were removed from the four covered vessels. After four days, "calycine" monads were found in all the first six vessels, and, in smaller numbers, the "springing" sort. Two days later the four vessels were examined; in three there were no calycine monads, and very few in the fourth; all exhibited the springing monads. The reason of this is probably to be found in the fact that the germs of the calycine monads are larger than those of the springing sort, and settled down first from their state of suspension in the air.

A Solar Distillery.—M. Mouchot lately described, at a meeting of the Paris Academy of Sciences, a very convenient solar alembic. The mirror is fifty centimetres in diameter, and the kettle holds one litre of