il, SEMINAL VEUMICULl. 293 



was remnrked in a former obfervation, 1 1 March. 

 I particularly attended to the diminution of their 

 motion, in proportion to the time that the iluid 

 had been expofed to the air. Scarcely has it 

 come from the animal when the corpufcula are 

 feen in great agitation, darting througli it with vaft 

 rapidity, and ofcillating to both fides. This ac- 

 tivity infenfibly decreafes ; fo that if they at firft 

 defcribe a certain given fpace in a fecond, — -in a 

 quarter of an hour, they do not traverfe a third 

 of it in the fame time, ^fhe arcs of ofcillation 

 become fuccelTively fmaller ; and at laft, the mo= 

 iion of the corpufcula is reduced to a languid 

 vibration of the body and appendage, without 

 any change of pofition. The vibration difap- 

 pears, and the appendage remains extended in a 

 ilraio-ht line, after the m.anner of thefe beinn-So 



Many aquatic animals of the apodal clafs tranf- 

 port themfelvfis by contorfions of their members 

 vibrating and ofcillating from fide to fide : and 

 indeed one can pofitively affirm, that the anterior 

 part of the body is puflied forward, and moves 

 progreffively by the contorfions and ofcillations 

 of the poflerior part. I paid the flridefl atten- 

 tion to difcover whether the anterior part of the 

 corpufcle was pufhed forward by ofcillations of 

 the appendage. When in very rapid motion, 

 the quicknefs of the mutual vibrations of the bo- 

 jdy and appendage render it impoffible to be dif- 

 T 3 trndW 



