POPULAR SCIENCE MONTHLY.
races are specifically different. The late Prof. Charles V. Riley distinguished twenty-two different broods of cicadas in the United States, seven of which appertain to the thirteen-year period (Cicada tredecem).
The Bureau of Nature Study of Cornell University is making a praiseworthy effort to interest children in caring for birds, or, as its circular has it, treating them as "summer boarders." It publishes a leaflet entitled The Birds and I, which it sends free to teachers who ask for it and who will give it to their pupils. It has pictures of various styles of bird houses, which may serve as patterns for the construction of homes for the summer guests. "The kind of birds," the interesting circular of the bureau says, "that will set up housekeeping in the homes that you provide will harm no one. They are never cross, never throw stones or rob us, but are always happy and have cheerful songs. We are always kind to people having such dispositions, and why should we not be so to birds as well?" The bureau invites correspondence from boys and girls disposed to entertain birds.
The National Geographic Society offers prizes of one hundred and fifty dollars and seventy-five dollars severally for the first and second best essays relating to pre-Columbian discoveries and settlements of the Norsemen on the mainland of North America, and the location of the lands mentioned in the Icelandic Sagas, the competition to close December 31, 1899. The essays sent in should be typewritten in the English language, not exceeding six thousand words in length, and may be accompanied by maps and illustrations for explanation of the text, but not for embellishment. The committee of awards consists of Mr. Henry Gannett, Prof. Albert Bushnell Hart, Mrs. Anita Newcomb McGee, Prof. John Bach McMaster, and Coast Survey Superintendent Henry S. Pritchet.
Experiments by a German naturalist, Herr Albrecht Bethe, summarized in the Revue Scientifique, upon recognition of one another by ants, confirm the opinions of Lubbock, McCook, Forel, and others that they are guided by the sense of smell. Herr Bethe found that an ant "whitewashed" with liquid of ants of its own nest was well received by its fellows when it went among them; but when the liquid of ants of a different nest was applied it was attacked at once. An ant washed with alcohol, next with water, and then with the liquid of a strange species was well received in a nest of that species, although it was much smaller than any of the individuals composing it. Another ant washed with alcohol and water, dried, and immediately returned to its fellows of its own nest, was attacked by them; but when kept for twenty-four hours after drying, or long enough to recruit itself, was received by them.
The following tables are taken from a paper by Dr. J. Richardson Armstrong in a recent Lancet, describing his experience with diphtheria antitoxine in private practice in treating one hundred and twenty-two cases of diphtheria:
|Total number of cases treated from June 27 to Dec. 17, 1897||42||36||6|
|Severe cases; antitoxine injected||22||20||2|
|Mild cases; antitoxine not injected||20||16||4|
|Total number of cases treated, January 1 to December 31, 1898||80||77||3|
|Severe cases, injected||55||54||1|
|Mild cases, non-injected||25||23||2|
In answer to the question, Should every case of diphtheria be treated with antitoxine, Dr. Armstrong says: "Some of the cases are sufficiently mild not to need it, so I will not go so far as to say that it isessential to inject in every case, although I would call it an excellent practice to