the animal is unable, either from exhaustion or other reasons, to produce that secretion whose stench is its great defense, its bite is productive of a highly-dangerous rabies, often causing death with some of the terrible symptoms of hydrophobia. We have thus authenticated the fact that rabies, capable of being given by the inoculation of a bite, is communicable by the canines, felines, and the mustelidæ families.
How Plants imbibe Ammonia.—From a series of experiments made by Adolf Mayer, it appears that plants have the power of absorbing ammonia through their aërial parts. The experiments were made on plants growing in such a manner that no ammonia could reach their roots directly, while the leaves were subject to its action, in either a gaseous or dissolved condition. It was observed, however, that the plants did not thrive when the access of ammonia to the roots was entirely prevented.
Reproduction of Organs in Fish.—Darwin, in his "Animals and Plants under Domestication," states, on the authority of Frank Buckland, that, when portions of the pectoral and tail-fins of various fresh-water fish are cut off, they are perfectly reproduced in about six weeks. This phenomenon of regeneration was recently observed in the aquarium of the Boston Young Men's Christian Union, by F. W. Clark, who communicates to the American Naturalist an interesting note on the subject. It appears that, in the spring of 1873, a fish-fungus made its appearance in the tank, and several fine fishes died. Among the specimens attacked by the fungus was a young goldfish, which, by some unknown means, had lost its tail-fin. The fungus covered the whole stump of the tail; the fish became sick, and was apparently dying. Mr. Clark's attention having been called to the case, he at once concluded that he had some parasite to deal with, and resolved to exterminate it. He applied a few drops of nitric acid to the tail-stump, allowing it to remain a moment or two, after which he rinsed it off in clean water, and put the fish back in the tank. The parasite, of course, was killed; the patches of fungus sloughed off, and the fish was soon well. In the course of a few days. he thought he saw the fungus again appearing on the affected part; but, on looking closely, found that the appearance was really due to the growth of new rays. A month later, a new tail-fin, about a fourth of an inch long, had appeared, and, three months from the time of the experiment, the fish was undistinguishable from others of the same species in the aquarium.
The American Association for the Advancement of Science will hold its twenty-third annual meeting this year at Hartford, commencing at ten o'clock, on Wednesday, August 12th. Members must furnish the permanent secretary, F. W. Putnam, Salem, Mass., with complete titles of all the papers they propose to present during the meeting, together with an estimate of the time required for reading each paper. Each title must be given on a separate slip of paper, with the full name of the author. The titles must be furnished to the secretary before the day appointed for the Association to convene. The Association will at this meeting accept the act of incorporation, giving it a legal existence. Another matter to come before it for deliberation will be the new constitution. From the American Naturalist we learn that a monograph on "Fossil Butterflies," by Mr. Scudder, is soon to be published by the Association, the necessary funds having been voted by the committee on Mrs. Thompson's gift. The officers elected for the Hartford meeting are the following: President, Dr. J. L. Le Conte, Philadelphia; Vice President, Prof. C. S. Lyman, New Haven; Permanent Secretary, F. W. Putnam, Salem, Mass.; General Secretary, Dr. A. C. Hamlin, Bangor; Treasurer, William S. Vaux, Philadelphia.
A correspondent of Land and Water relates an instance of a brood of chickens being cared for by a cat. This brood, having been hatched very early in the season, was taken from the hen and placed in a basket near a kitchen fire. Soon the chicks were missing, and, on search being made, were found in an up-stairs room, kindly tended by the domestic cat, being huddled close to her warm fur. They were returned to the kitchen, and, the cat still claiming them, she was left in possession of her adopted brood, which she raised to chicken-hood. As they grew up the cat would accompany them in their out-of-door rambles, lying in the sun, and fondly watching them.
Good results have been obtained in the utilization of sewage at Dantzic The land