128 EEVIEWS. 



Cerceris merely relinquishes her captive for an instant at the en- 

 trance, in order to turn round and crawl backwards — thus more 

 conveniently pulling him after her. "Wliy then should the Sphex 

 ]5ersist in paying this domiciliary visit before introducing her victim ? 

 Pcrhajjs through apprehension lest one of the Tachytes, who make 

 use of the same kind of cells for their offspring, and are accustomed 

 to provision them in like manner, should have taken advantage of 

 the lawful owner's absence, to deposit an egg in the cell ready scooped 

 out. But however this may be, the manoeuvres of the Sphex are in- 

 variably the same. M. Fabre's experiments on this head are very 

 curious. He took advantage of her momentary absence to remove 

 the grasshopper, and place it at a few inches distance. Tlie pro- 

 prietor returned, uttering her usual cry, looked anxiously about, and 

 finally, perceiving her prey, dragged it back to her door, and ■i)laced 

 it again in precisely its former position ; then leaving it, descended 

 as before into her nest. The same process was repeated by M. Fabre 

 thirty or forty times, in the hope that the Sphex, taught by expe- 

 rience, would cease to lose sight for a moment of her captive and 

 convey it at once into the earth. But the perseverance of the insect 

 triumphed over that of the philosopher; or rather, her acts not being 

 dictated by reason, she knew not how to leave the path marked out 

 for her by instinct. 



In the case also of a Sphex alhisecta, an inflexible adherence to 

 settled laws in this respect was strikingly manifest, presenting a 

 still more curious instance of the rigidity of instinct and its 

 inapplicability to imusual conditions. Having, in the course of 

 one^ of his experiments, removed her victim from the sight of a 

 Sphex albisecta, M. Fabre observed the insect, after seeking vainly 

 in all directions, descend for a few instants into her cell, and then 

 emerging, proceed to cover up the entrance, as if her task were 

 now satisfactorily accomplished ; a striking exemplification of the 

 manner in which acts of instinct depend one upon another, and 

 admit of no variation, notwithstanding that their object may be 

 entirely defeated by the alteration of siu'rounding circumstances. 

 In the normal state of things, observes M. Fabre, the Sphex pur- 

 sues her prey, lays an egg and closes her nest ; an accident deprives 

 her of her booty ; no matter — that part of her duty is over, she there- 

 fore performs the remainder, and shuts up the unlucky egg quite 

 unprovided for. Tliink of the melancholy fate entailed by maternal 

 stii])idity upon the helpless little new-born lai'va— fancy it emerging 

 from the shell, in the full expectation of a satisfactory meal, and tlie 

 miserable disappointment awaiting it, ending in despaii' and a lin- 

 gei'ing death. Many larvc'e must so perish; for the case above- 

 mentioned is by no means exceptional. M. Fabre repeated the 

 experiment several times, meeting almost invariably with the same 

 results; aiul on o])ening the nests he frequently found cells either 

 su])])]icd inadetpiately with provisions, or containing none at all. 



The rest of this paper is chiefly anatomical, and devoted to an 



