Page:Popular Science Monthly Volume 3.djvu/412

398 under which the girls are kissed in the Christmas-games, is a sort of "pious fraud," being imported in enormous quantities into England from Belgium in immense crates. In Belgium it is plentiful on old and exhausted apple-trees. Indeed, the real Druid mistletoe of the English oaks has become almost like that ancient personage, a thing of the past.

A Viviparous Fly.—In the American Naturalist is an interesting account, by Prof. Lockwood, of the Sarcophaga carnaria, a species of flesh-fly, which brings forth its larvæ or maggots alive, instead of laying eggs. Fine engravings are given of the fly, its pupa, and larva. The professor succeeded in rearing some of the grubs until they became perfect flies, it requiring 13 days to effect the complete series of changes. One of the grubs he put alive into 95 per cent alcohol, in which fluid it sustained life 134 minutes. This larva was six days old. One seven days old was placed in turpentine, where motion ceased only at the end of 27 minutes. One in essence of peppermint lived 70 minutes; and another, in Fowler's solution, only ceased to manifest motion at the end of 53 minutes.

From these experiments Dr. Lockwood is led to remark: "In the light of such facts, what reprobation is too severe upon the useless and cruel practice of drenching horses with violent medicaments for the bots? The ailment thus known is due to the presence in the animal's stomach of the larvæ of the bot fly (Gastrophilus equi), which clings to the walls of the stomach by its formidable mouth-hooks." As further evidence of the tenacity of the larvæ of certain flies, this naturalist says: "Long ago my attention was called to the tenacity of larval life when exposed to poisons, I was forced by the claims of justice to take part in a toxicological examination of the internal organs of a person who had been nine months buried. These were put in a large glass jar, and the jar filled with water. It was summer. In three or four days, I noticed the presence of a great number of large white larvæ, doubtless of the common blow-fly. We obtained enough bichloride of mercury to establish the fact that the woman had died by taking a very large quantity of this terrible poison. Naturalists know how well this drug will preserve animal tissues. And in this case, the blood in the capillary vessels was of a bright color, as if fresh. And, despite the presence of so much poison, the larvæ grew. Whether they would change to flies, I cannot say. Another case is that of a horse of a friend, which was injured by accident and had to be killed. The animal was opened, and the walls of the stomach were found to be covered with the larvæ of the bot-fly. A piece of the stomach was spread on a board in the sun. Some turpentine was poured on the larvæ but with little effect, as not one was detached, when it was examined an hour afterward. Some whale-oil was poured on them. They let go immediately, and soon all died."

This subject of the tenacity of life in insects has lately engaged the attention of Belgian naturalist Plateau. We give his more important results. At the bottom of an open vessel holding a little over a quart of fresh water he placed a very small vessel containing the insect, and covered it with a piece of cotton netting. Terrestrial insects placed in these conditions, impelled by their specific lightness, rise to the lower surface of the net-work. The movements of their legs soon cease, they do not appear to suffer, and quickly grow torpid. The aquatic Coleoptera and Hemiptera, on the contrary, instead of submitting passively to their fate, endeavor to quit their prison swim rapidly about, try to come to the surface, and so struggle on till they are quite exhausted and lie at the bottom as if dead.

M. Plateau, after keeping the insects thus under water for a certain length of time, took them out and dried them on blotting-paper. He found that the terrestrial Coleoptera recovered after immersion in several instances, for 96 hours, while the aquatic swimming Coleoptera and Hemiptera had no such power of resistance to asphyxia. The author accounts for this by the rapid waste of oxygen caused by the greater activity of the aquatic insects. He also tried the effects of cold heat on the aquatic insects. It was found that these insects, in the latitude of Belgium can live