42 ME. NEWPOET ON THE NATUEAL HISTOET 



several days in coniinement, and especially when there has not 

 been communion with the other sex. It is given out from the 

 ventral siu'face of the last three segments of the body, which are 

 almost transparent, and have no dark pigment in their texture ; 

 but it is most intense in the anterior half of the tenth and eleventh 

 segments, on each of which it forms two broad bands extending 

 across the whole siu'face. In the twelfth or last segment it is 

 feeble, and appears merely as two bright spots, one on each side 

 of the surface, and each about the size of a moderate pin's head. 

 The light is most intense in those females which have passed 

 through their metamorphosis only within the last two or three 

 days, and have not yet paired : in these it is sometimes so power- 

 ful, that I have been able to read small print for an hour by my 

 watch in the darkest night. It is given forth most intensely in 

 faint flashes immediately the insect becomes stationary after loco- 

 motion, and usually when it has crept up a blade of grass, or 

 crawled along a slight eminence in its native haunts ; if the insect 

 is watched at that time, it may frequently be observed to coil the 

 extremity of its body upwards, exposing its light most to view, 

 and turning it to the right and to the left, as if to use it as a 

 beacon for the wandering volant male. Even when she is perfectly 

 stationary on the ground for a few minutes, the female rests with 

 the extremity of her body turned to one side, so as still to show 

 the light ; though if the male continues absent, she seldom remains 

 long in one place or position, but continues alternately to wander 

 on and to rest, scintillating her light more and more intensely at 

 intervals. 



I have witnessed these circumstances repeatedly both in the 

 natural haunts of the insect and in confinement ; and am scarcely 

 prepared to regard them as a direct act of the will, but rather as 

 an evolution of instinct through the direct stimulus of vital causes, 

 precisely as I regard what is in like manner believed to be a volun- 

 tary extinction of the light (Kirby and Spence, vol. ii.) at the 

 moment of capture or of sudden contact with a foreign body. At 

 the instant of such contact the entire body of the insect is con- 

 tracted and shortened, more especially on the ventral siu-face ; and 

 not only are the light-giving segments drawn one within the other, 

 but the luminous organs within them are simply removed from 

 immediate contact with the tegument, and are not, as supposed by 

 Murray * and Miiller, hidden behind opake parts : possibly the 



* See Miuray's Experimental Researches on the Light of the Glowworm. 

 Edinb. 1826. 



