PREFACE. 



THE Author having been appointed to the Chairs of Vege- 

 table and Animal Physiology and Entomology, in the State 

 Agricultural College of Michigan, has felt the want of a suita- 

 ble text-book, for the use of his students, and not being aware 

 of any existing work on the plan he considers essential for the 

 acquisition of these subjects, he has prepared the accompany- 

 ing volume to aid him in his labors, and to fulfil a request, 

 previously made to him by the Superintendent of Public 

 Instruction of the State of Michigan, the Hon. Ira Mayhew, 

 to write such a work. 



The " Botanies " hitherto published, are insufficient as 

 physiologies ; and the Animal physiologies, as yet prepared 

 " for the use of Schools," are simply epitomized treatises on 

 Human anatomy, and are generally too technical and obscure 

 to be available for the purposes of popular instruction. 



This latter subject, a distasteful one, even to Medical 

 Students, who rarely learn it, must necessarily prove a severe 

 tax to the youth of both sexes, who throng the public and 

 private schools of the country, whilst many of the illustrations 

 supposed to be necessary to these books, are, to say the least 

 of them, most uninviting. 



The attempt to teach only Human Physiology, like a 

 similar proceeding in regard to anatomy, can only end in 

 failure: whereas, if the origin (so to speak) of the organic 

 structures in the animal kingdom, be sought for and steadily 

 pursued through all the classes, showing their gradual com- 

 plication, and the necessity for the addition of accessory 

 organs, till they reach their utmost development and cul- 



