io8 POPULAR SCIENCE MONTHLY. 



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 hifasciatus nesting in a hedge at Chatelle- 

 rault in abandoned snail shells. Some shells contained as many 

 as three cocoons. This year, at Algiers, I found bulimus contain- 

 ing 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 al- 

 ways dig. I have long observed a little pompilus at Chatellerault 

 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 

 showiDg these tendencies for many centuries. The walks of ih.Q 

 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. P^rez, in his con- 

 tributions to the apian fauna of France, has studied the para- 

 sites 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 pom- 

 pilides. If we succeed in this, we shall perhaps have answered 

 the challenge sent out in his Souvenirs by the entomologist of 

 S^rignan : " Let them show me a species in the course of trans- 

 formation.'' Translated for the Popular Science Monthly from 

 the Revue Scientifique. 



A CURIOUS 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 whicb it had been imbedded two months. The hand was placed 

 upon one of the poles of an electro- magnet, and a current giving an attract- 

 ive 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 oflP, came out and adhered to the magnet, the whole 

 operation having been performed without pain or loss of blood. 



* Die Hymenopfera Deuischland, etc. 



