PREFACE. 



minate in man, the study may (possibly) be rendered an 

 agreeable and interesting one, and be fruitful in profitable 



results. 



Throughout the accompanying pages, this principle has 

 been kept steadily in view, and it has been deemed of more 

 importance to impart solid and thorough instruction on the 

 few subjects discussed, rather than embrace the whole field 

 of physiology, and, for want of space, foil to do justice to any 



part of it. 



The development of the nutrimental organs, and of the 

 brain and nervous system, have been considered as of pri- 

 mary importance, and to the consideration of these topics 

 much space and great care have been devoted. The latter 

 subject has always been most difficult to understand, and the 

 attempt has been made by the Author, to popularize this 

 very abstruse subject; with what success remains to be 

 seen. 



In proof that the views above-enunciated are supported 

 by high authority, the opinions of the distinguished Haller, 

 and the late Baron Cuvier, are quoted; moreover, the 

 Authors of the best and most reliable treatise on human 

 physiology Todd and Bowman have adopted, and given 

 expression to the same opinion. 



u A knowledge of human anatomy alone, is not sufficient to 

 enable us to form accurate views of the functions of the vari- 

 ous organs." Before an exact knowledge can be formed of 

 the functions of most parts of living bodies, Haller says, that 

 " the construction of the same part must be examined and 

 compared in man, in various quadrupeds, in birds, in fishes, 

 and even in insects." 



Cuvier has compared the examination of the comparative 

 anatomy of an organ in its gradation from its most complex 

 to its simplest state, to an experiment which consists in re- 

 moving successive portions of the organ, with a view to 

 determine its most essential and important part. In the ani- 

 mal series we see this experiment performed by the hand of 

 nature, without those disturbances which mechanical violence 

 must inevitably produce. Thus we learn that one portion 

 of the nervous system, in those animals in which it has a defi- 



