[ 35 ] 

 yet the hard cruft with which they are 

 invefted, and their fhortnefs in flies and 

 other infects, would induce one to be- 

 lieve them not to be the organs of touch : 

 that they are tubular, and rllledwith air, 

 and fome kind of humour, appears from 

 the antennas of butterfties immerfed in 

 water. To come now to the terms of 

 the art. A knowledge of the external 

 parts of the body is firft to be eftablilh- 

 ed, which, after the method of anato- 

 mifts, we divide into head, trunk, ab- 

 domen, and extremities. 



S E C ■ T. VIII. 



Caput, the head» This part in infects 

 is without brain. The difference be- 

 tween the brain and fpinal marrow con- 

 .fifts in the former being a medullary 

 part organized. We do not deny the 

 F 2 exiftenee 



