that a soil is a laboratory and not a mine, is erroneous; for not only the facts adduced by them in previous papers, but the whole history of agriculture, so far as we know it, show that a fertile soil is one which has accumulated within it the residue of ages of previous vegetation, and that it becomes less fertile as this residue is exhausted.
Dr. Cobbold, an eminent authority on the subject, asserts that the danger of eating parasites in fish used as food is much exaggerated, and that there is extremely little of it. If the fish are only moderately boiled, the parasites will all be killed, and, if they are not, not one in a thousand of them will find itself at home enough in the human stomach to do any harm. Professor Huxley also declares that the thread-worm of the mackerel is harmless, and that the idea of its being a possible cause of cholera is sheer nonsense; and he thinks it outrageous that the suggestion has been made.
Masks of mica are made at Breslau for the use of workmen who are exposed to high temperatures, to acid vapors, or to metallic sparks. They are found to protect the eyes better than glasses, while there is space enough between them and the eyes to permit spectacles to be used also. The plates of mica are fixed in metallic supports protected with amianthus, and the neck and shoulders of the workman are covered with a hood of that substance.
The Eilsitt bridge, Lyons, France, is called "the singing-bridge," on account of the musical sounds it emits at different parts of its course, "when at particular moments one might believe it haunted by legions of invisible naiads pursuing the passengers with their plaintive melodies." The bridge is furnished with a stone parapet, which is pierced at intervals for light, with rectangular openings having their ends rounded off in semicircles. The effect of this passage, with the air-currents rushing through it, is that of a flute, of which the windows represent the holes. The tones vary considerably at times in intensity, with but little difference in their pitch.
The prairie-wolf has been introduced into Epping Forest, England, and appears to be breeding freely there. The animals have been confounded by some persons with cubs of the fox, and described by others as "strange animals from foreign parts." One of them was recently offered to Mr. Bartlett, Superintendent of the London Zoölogical Gardens, who, doubting whether it might not be a hybrid of some kind, visited the forest to learn something more about its real character. The less frequented parts of the forest seem well suited to the habits of the animals, and they promise to thrive.
Dr. Richardson has sounded a note of warning against the too hasty and complete acceptance of the bacillus theory for the origin of every kind of infection, to the neglect "of all the preceding clinical history." He asks: "Upon the evidence of how many or how few men does the bacillus hypothesis rest? On what reasoning does it rest? Who has separated, in relation to it, coincidence from causation?" To ask these questions, or to heed them, is not necessarily to question the validity of the bacillus theory, but simply to pause and review, and ask for the proof of it.
The question whether the water of a river like the Thames, when once polluted by sewage, can be made fit for drinking purposes, either by the oxidation incident to its own flow or by artificial filtration, was again up for discussion recently before the London Society of Arts. Dr. Frankland took the negative side upon it, and insisted that the Thames's supplies to London should be abandoned; while many eminent engineers and a few chemists positively contradicted both his data and his conclusions. Mr. W. Mattieu Williams suggests that the force of the latter gentlemen's opinions is somewhat detracted from by the fact that most of them are concerned in the construction of filter-beds and other engineering appliances for river-water purification, or in schemes for chemical precipitations.
The ice-plant of our ladies' window-baskets (Mesembryanthemum crystallinum) affords a striking illustration of the elective power which plants have of taking up by their roots from a complex soil the materials proper for them. M. Mangon has cultivated it for several years on the same ground with cabbage, celery, and other plants, and has found that, while the latter plants had their normal composition, the ice-plant, dried and burned, furnished an ash with an amount of chlorine and alkali that astonished him. From one hectare, or two acres and a half of ice-plants, he obtained 1,820 kilogrammes of ashes, containing 335 kilogrammes of chlorine, as much soda, and 588 kilogrammes of potash, the latter of which substances was capable of furnishing 863 kilogrammes of carbonate of soda, or nearly as much as is got from the incineration of one hectare's yield of the salt-works at Alicante. M. Mangon suggests that this plant might be cultivated for a potash-plant, and that it might be made serviceable in removing the excess of alkaline salts from salt grounds.
A correspondent of "Nature" writes from Java that, having recently killed one of the venomous snakes of that island, he noticed the tail of a second snake sticking from its mouth, and found that it had swallowed another individual of the same species, and nearly the same size with itself.
