158 INSENSIBILITY OF PLANARIA. 



other extremity, or tail, was somewhat pointed. The 

 ears were curved backwards, and finely dotted with 

 minute specks. It moved along with some rapidity, 

 chiefly by contraction of the margin, which was more 

 or less curled while the body kept in motion. On 

 being captured, it was put into a bottle of sea-water, 

 in company with some other animals, for the purpose of 

 further examination ; but one of these (I am uncertain 

 which) attacked, and actually eat off about half the 

 body of the Planaria before it was detected. The latter, 

 however, seemed to feel no inconvenience from the loss 

 of its hinder parts, and moved about as rapidly, and 

 with as much apparent ease and pleasure, as if nothing 

 had occurred. This insensibility to mutilation is a com- 

 mon character of these animals, and seems to show that 

 they have really, as well as apparently, no nervous cen- 

 tres. It is well known that if a Planaria be cut in 

 pieces, all the several parts will continue to live and 

 move about ; and each of them, however small, will, in 

 due time, become a perfect animal, complete in all its 

 parts. But what is still more curious, it has been ob- 

 served that if the Planaria be mutilated while in 

 motion, its separate parts will continue to move in the 

 same direction as the animal had been following be- 

 fore the mutilation. This is a very curious fact, as the 

 parts of most other animals which are similarly viva- 

 cious, when broken up, move off in opposite directions. 

 According to the observation of anatomists, the flesh 

 of the Planaria is of a very simple structure, nearly 

 gelatinous, with little or no trace of muscular fibre ; 

 and no traces of nervous filaments have been clearly as- 

 certained. Some species, however, have coloured specks 



