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Page:Popular Science Monthly Volume 15.djvu/638

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THE POPULAR SCIENCE MONTHLY.

The cause of the fly becoming so firmly attached to dry surfaces is this: The two pulvilli which, with two strong curved claws (perhaps best seen with the flesh-fly, Musca vomitoria, as a subject), terminate

PSM V15 D638 Maggot of house fly.jpg
Fig. 4—Maggot of House-Fly, July 29, 1878, x 25.

the foot, are surrounded by a fringe of tubular hairs, each ending with a disk or sucker, through which a glutinous fluid exudes. These form the points of attachment, enabling the insect to walk in any position, the action of the two claws detaching these points as the fly moves along.

When the ravages of the parasite have sufficiently weakened the fly by the destruction of its viscera, etc., it becomes incapable of active movement, and, remaining too long in a place, the viscid fluid continues to exude, and then the fly "sticks to the wall."—Science Gossip.

 

FOOD AND FEEDING.
By Sir HENRY THOMPSON.
III.

I HAVE already said that, among all civilized nations, wine in some form has for centuries been highly appreciated as a gastronomic accompaniment to food. I can not and do not attempt to deny it this position. Whether such employment of it is advantageous from a dietetic or physiological point of view is altogether another question. I am of opinion that the habitual use of wine, beer, or spirits is a dietetic error, say, for nineteen persons out of twenty. In other words, the great majority of the people, at any age or of either sex, will enjoy better health, both of body and mind, and will live longer, without any alcoholic drinks whatever, than with habitual indulgence in their use, even although such use be what is popularly understood as moderate. But I do not aver that any particular harm results from the habit of now and then enjoying a glass of really fine, pure wine—and, rare as