INTERNAL ANATOMY OF INSECTS. 19 
spinal marrow, all the sensations of the animal are con- 
veyed, and in which all its perceptions terminate. The 
nerves and spinal marrow are merely the roads by which 
the sensations travel; and if their communication with 
the brain, by any means be cut off at the neck, the whole 
trunk of the animal becomes paralytic, evidently proving 
that the organ by which it feels is the brain. This, how- 
ever, is so far from being the case in insects, that in them, 
if the head be cut off, the remainder of the body will con- 
tinue to give proofs of life and sensation longer than the 
head: both portions will live after the separation, some- 
times for a considerable period; but the largest will sur- 
vive the longest, and will move, walk, and occasionally 
even fly, at first almost as actively without the head, as 
when united to it. Lyonnet informs us, that he has seen 
motion in the body of a wasp three days after it had been 
separated from the head; and that a caterpillar even 
walked some days after that operation; and when touched, 
the headless animal made the same movements as when 
intire?. Dr. Shaw has observed—an observation con- 
firmed in Unzer’s Kleine Schreiften,—that if Scolopendra 
electrica (Geophilus Leach) be cut in two, the halves will 
live and appear vigorous even for a fortnight afterwards ; 
and what is more remarkable, that the ¢az/ part always sur- 
vives the head two or three days>. ‘The sensorium com- 
mune of insects, therefore, does not, as in the warm-blooded 
animals, reside in the brain alone, but in the spinal mar- 
row also. It was on this account probably that Linné 
2 In Lesser Insecto-theol. 11. 84. note *. 
> Linn. Trans. ii. 8. Aristotle had observed this vitality of insects, 
and that that of the myriapods is greatest. Hist. Animal. 1. iv. c. 7. 
De Respiratione, c. 3. Reptiles have also this faculty. NM. Dict. 
d’ Hist. Nat. xxix. 161. 
ce 
