Page:Popular Science Monthly Volume 50.djvu/120

108 nest, too, a very great adaptation of instinct to conditions exists among the pompilides. They turn everything to profit.

Taschenberg says that the Pogonius nest In the sand. I have found Pogonius bifasciatus nesting in a hedge at Châtellerault in abandoned snail shells. Some shells contained as many as three cocoons. This year, at Algiers, I found bulimus containing cocoons which have not hatched at this writing, but which strongly resemble the cocoons of my pogonius. If Taschenberg has not made a mistake, the insect is a digger that does not always dig. I have long observed a little pompilus at Châtellerault which I have not been able to identify. I have seen it nesting almost everywhere—in snail shells, in the rotten mortar of old walls, and in worm-eaten wood, digging when it had no other way. One day it even had the audacity, while we were at lunch, to bring its spider to my sister's hair.

We are therefore, it seems to me, contemplating an eminently variable instinct, which, joined to the tendencies to parasitism of which I have just spoken, suggests that a parasitical branch may be even now detaching itself from the pompilus type.

The pompilides, or some among them, have possibly been showing these tendencies for many centuries. The walks of the garden near Algiers are crowded in October with small spiders which pass the day hidden in holes closed by a stone or a clod. I have observed that a little Salius knew very well how to open this retreat, go in, and kill the inmate. Prof. Pérez, in his contributions to the apian fauna of France, has studied the parasites of bees in a masterly manner, but he has almost omitted the study of instinct in the formation of parasitism. I have no more than suggested the question, but I believe we might easily give an acceptable answer to it with the help of the pompilides. If we succeed in this, we shall perhaps have answered the challenge sent out in his Souvenirs by the entomologist of Sérignan: "Let them show me a species in the course of transformation."—Translated for the Popular Science Monthly from the Revue Scientifique.

experiment is recorded in La Nature by M. F. Crestin, in which, by the application of a magnet, he extracted a needle from a woman's hand, in which it had been imbedded two months. The hand was placed upon one of the poles of an electro-magnet, and a current giving an attractive force of three grammes was applied for about two hours at a time. After nine sittings, or about twenty hours of magnetic action, the needle, with the point broken off, came out and adhered to the magnet, the whole operation having been performed without pain or loss of blood.