Y,2- 



PREFACE. 



IN the preface to the first part. of this work, published a 

 little more than a year ago, the author announced his inten- 

 tion of writing an extended treatise upon human physiol- 

 ogy ; and the present volume, devoted to subjects connected 

 with the great functions of digestion and absorption, is now 

 presented, as the second of the series. As stated in the 

 preface to the first volume, the separate parts of the work 

 are intended to form distinct treatises, devoted respectively 

 to natural subdivisions of the science of physiology ; each 

 one being complete in itself, but the entire series embracing 

 all the subjects usually regarded as belonging to human 

 physiology. The manner in which the first part has been 

 received, and the experience of the author in the prepara- 

 tion of the present volume, have encouraged him. in carrying 

 out the original plan of the work. To give to every sub- 

 division of physiology that careful reflection and critical 

 study, which alone could enable one to form a calm and 

 dispassionate judgment upon the difficult questions which 

 are constantly arising, involves an amount of time and 

 patient labor which might well discourage the most en- 

 thusiastic student. A work of such magnitude, however, 



