20 INTRODUCTION. 



It would be equally presumptuous and unreasonable 

 should I, with a late writer on this subject, " exhort the 

 reader to be particularly on his guard against loose and 

 indefinite expressions;" but I perfectly agree with him 

 that they are the bane of all science, and have been 

 remarkably injurious in the different departments of 

 physiology. 



