40 MEMOIR OF JOHN HUNTER. 



with another : this union forms in some only one ca 

 nal, as in the cod, salmon, ling, &c., and in others a 

 tolerably large cavity, as in the ray kind. In the 

 tick, there is an oblong bag, or blind process, which 

 js an addition to these canals, and communicates 

 with them at their union. In the cod, &c. this union 

 of three tubes stands upon an oval cavity ; and in 

 the jack there are two : the additional cavities in 

 these fishes appearing to answer the same purpose 

 with the cavity observed in the ray, or cartilaginous 

 fishes. 



" 1 will here mention an experiment, to shew that 

 sounds affect fishes very much, and is one of their 

 guards, as it is in other animals. In the year 1762, 

 when I was in Portugal, I observed in a nobleman's 

 garden, near Lisbon, a small fish-pond, full of diffe- 

 rent kinds of fish. The bottom was level with the 

 ground, the pond having been made by forming a 

 bank all round, and it had a shrubbery close to it. 

 Whilst I lay on the bank, observing the fish swim- 

 ming about, I desired a gentleman who was with me 

 to fire a loaded gun from behind the shrubbery. 

 The reason for desiring him to go behind the shrubs 

 was, that there might not be the least reflection of 

 fight. The moment the report was made, the fish 

 teemed to be all of one mind, for they vanished in- 

 stantaneously, raising a cloud of mud from the bot- 

 tom In about five minutes after, they began to re- 

 appear, swimming about as before." 



During Mr Hater's absence with the army, th 



