Queries and Answers. ^81 



horse, and over that carcass stood (as the guide well knew) the lion, whom 

 the condors were eyeing with envy from their airy height. The signal of 

 the birds was to him what the sight of the lion alone could have been to 

 the traveller, a full assurance of its existence." 



Doubtless the rooks could distinguish some marked peculiarity in the 

 plantains and other plants attacked by the grubs ; although, to an unac- 

 customed and less interested eye, the " verdure of the pasture might remain 

 uniform, and without any sensible appearance of withering or decay." — 

 J.S.Henslow. Cambridge y Feb A. im\. 



Electricity of the Caterpillar of Cerura vinula. — Animal electricity (that 

 is, the voluntary power of communicating electricity) is one of the strangest 

 phenomena in nature ; and this seems to accord so much with the general 

 sense of mankind, that any new fact of this kind is listened to with inat- 

 tention, if not with incredulity. It has been allowed to be ascertained in 

 some fishes, and in one insect, a beetle from Brazil. What I am going to 

 relate establishes the existence of the power among caterpillars, at least to 

 the conviction of my own mind. 



Observing the leaves of a young poplar, of the species P. canescens, to 

 be much destroyed, I was led to examine the cause. Two large sorts of 

 caterpillars were feeding upon it, both to me, at that time, unknown ; and the 

 name of one of them I am still ignorant of: the other is now called Cerura 

 vinula. I broke off two twigs, with one of each, and was carrying them 

 home : the Cerura showed decided symptoms of irritation, which particu- 

 larly drew my attention. It began to contract itself, drawing itself closely 

 together, and by degrees elevated and extended its bifurcated tail ; and 

 there were slowly protruded from each of the points bright red filaments, 

 about one eighth of an inch long, and irregularly bent to one side. In a 

 short time I felt a sudden tingle along my arm, which made me stop with 

 surprise. Suspecting, however, that this might be imaginary, I again pro- 

 ceeded; and, shortly after, I felt another shock, which made me almost 

 involuntarily throw the twig with the creature upon the ground. As I was 

 near the house, and one of the children with me, I sent her for a wine- 

 glass, in which I put the caterpillar, which immediately drew in its tails to 

 their original parallel position, and coiled itself in the bottom. On enter- 

 ing the house, I set the one in the glass on the chimney-piece ; and, as the 

 other was more lively, I passed a minute or two in examining it with a 

 pocket lens. I then turned to the Cerura from which I had the electrical' 

 shocks ; and as it had remained coiled together when I set it down, I was' 

 surprised to see the glass empty, and the insect gone : it had fallen upon' 

 the carpet ,• and I was sorely disappointed to find that the child had crushed 

 it with her foot, displacing the intestines, and along with them a clear gela- 

 tinous matter, consisting of a great number of short cylinders. Upon at- 

 tempting to lift one of these with the point of a pin, I found that I pulled 

 more after it. They were attached to each other by small ligaments ; and 

 I was agreeably astonished to discover that they separated from the mass 

 exactly after the manner that the links of a land-measurer's chain are ex- 

 tended, and had been so arranged in the body of the caterpillar, forming an 

 organ, composed of these cylinders, at right angles with its length. I con- 

 vinced myself that this apparatus had nothing to do with the viscera of 

 the insect, and remain satisfied (not altogether philosophically, I must 

 acknowledge) that they composed the electrical organ by which I received 

 the shocks. 



As I have never been so lucky as to procure another of these caterpil- 

 lars (although in 1826 they abounded in great numbers, as 1 learned after- 

 wards, on a plantation of poplars at Thirlstane, the seat of Lord Napier, 

 on the Ettrick), I would, therefore, be glad to hear, through your Magazine, 

 if any analogous fact relating to this well known caterpillar has been ob- 

 served. — If. !>. Selkirkshire. iV^or. 1830. . 



