Page:Popular Science Monthly Volume 43.djvu/147

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glass; clear white breath figures of the device will appear. A piece of paper is folded several times each way to form small squares, then spread out and placed under glass; the raised lines of the folds produce white breath traces, and in one instance a letter-weight that was above left a latent mark of its circular rim. Some writing made on paper with ordinary ink and well dried, left a very lasting white breath image after a few hours' contact. Plates of glass lying for a few hours on a table cover worked with silk acquired strong white figures from the silk. Two cases have been reported where blinds with embossed letters left a latent image on the window near which they lay; it was revealed in misty weather, and had not been removed by washing. A glass which has lain above a picture for several years, but has been kept from contact by the mount, will often show on its inner side an outline of the picture, always visible without breath. The words white and black in the descriptions of the impressions relate to the adherence of the breath to the reliefs (white) or its non-adherence (black). The exact cause of the phenomenon is not known, but is supposed to lie in some of the unknown regions of molecular agency.

Exclusive Communities.—The number of ants dwelling together in a community, according to Sir John Lubbock, is sometimes as great as five hundred thousand. They are always friendly toward each other, no quarrel ever having been observed between two ants, members of the same community. They are, however, very exclusive, and regard an immigrant with horror. When an ant of the same species belonging to another nest appears among them, he is promptly taken by the leg or antenna and put out. It would naturally be surmised that this distinction was made by means of some communication. To test whether they could recognize each other without signs, attempts were made to render them insensible, first by chloroform and afterward by whisky. "None of the ants would voluntarily degrade themselves by getting drunk." Finally, fifty ants were taken, twenty-five from one community and twenty-five from another, and dipped into whisky until intoxicated. They were then appropriately marked with a spot of paint and placed on a table where the ants from one nest were feeding. The sober ones noticed the drunkards and seemed much perplexed. At length they took the interlopers to the edge of the moat surrounding the table and dropped each one into the water. Their comrades, however, they carried home and placed in the nest, where they slept off the effects of the liquor.

The Comma Bacillns, Cholera, and Sanitation.—Experiments by Prof, von Pettenkofer and Prof. Emmerich, in which they swallowed fresh cultures of comma bacillus upon empty, neutralized stomachs, show conclusively to von Pettenkofer that the comma bacillus, during its sojourn in the intestine, does not produce the specific poison that causes Asiatic cholera. This agrees with the results obtained by Bouchard, who was able to induce the symptoms of cholera in rabbits by giving them the excreta of human cholera patients, but not by giving them pure cultures of comma bacilli or their metabolic products. While he does not deny that the comma bacillus has some etiological importance, von Pettenkofer can not believe it is the x which, without the assistance of y, can cause epidemics of cholera; and he reiterates his wellknown views on the influence of the soil, especially in connection with the rainfall. His practical teaching may be summarized in the formula that it is the y—that is, the local physical and sanitary conditions—that must be attended to; each place must, in short, be made cholera-proof by sanitation.

Children and Flowers.—In a paper read before the Society of American Florists, on training children to love and cultivate flowers, Mr. Robert Farquhar argued that we could either stifle or strengthen the love of Nature which is planted in every young heart. If we encourage and cultivate this love the mind of the growing child will be opened to the beauties of Nature, and we shall in this way provide for it a means of healthy exercise out of doors and a source of delightful recreation all through life. Children should have gardens of their own to care for, and they should be instructed in garden practice. They should be allowed to sow the seed and care for the plants themselves, although they should be directed in all these operations.