viii PREFACE TO THE FIRST EDITION 



But by so doing no adequate idea of the present state of physi- 

 ological science would have been conveyed; in many directions it is 

 much farther traveled and more completely known than in others ; 

 and, as ever, exactly the most interesting points are those which lie 

 on the boundary between what we know and what we hope to 

 know. In Gross Anatomy there are now but few points calling for 

 a suspension of judgment; with respect to Microscopic Anatomy 

 there are more ; but a treatise on Physiology which would pass by, 

 unmentioned, all things not known but sought, would convey an 

 utterly unfaithful and untrue idea. Physiology has not finished 

 its course. It is not cut and dried, and ready to be laid aside for 

 reference like a specimen in an Herbarium, but is comparable 

 rather to a living, growing plant, with some stout and useful 

 branches well raised into the light, others but part grown, and 

 many still represented by unfolded buds. To the teacher, more- 

 over, no pupil is more discouraging than the one who thinks there 

 is nothing to learn; and the boy who has "finished" Latin and 

 " done " Geometry finds sometimes his counterpart in the lad who 

 has "gone through" Physiology. For this unfortunate state of 

 mind many Text-books are, I believe, much to blame: difficulties 

 are too often ignored, or opening vistas of knowledge resolutely 

 kept out of view: the forbidden regions may be, it is true, too 

 rough for the young student to be guided through, or as yet path- 

 less for the pioneers of thought ; but the opportunity to arouse the 

 receptive mental attitude apt to be produced by the recognition 

 of the fact that much more still remains to be learned to excite 

 the exercise of the reasoning faculties upon disputed matters and, 

 in some of the better minds, to arouse the longing to assist in add- 

 ing to knowledge, is an inestimable advantage, not to be lightly 

 thrown aside through the desire to make an elegantly symmetrical 

 book. While I trust, therefore, that this volume contains all the 

 more important facts at present known about the working of our 

 Bodies, I as earnestly hope that it makes plain that very much is 

 yet to be discovered. 



A work of the scope of the present volume is, of course, not the 

 proper medium for the publication of novel facts; but, while the 

 " Human Body," accordingly, professes to be merely a compilation, 

 the introduction of constant references to authorities would have 

 been out of place. I trust, however, that it will be found through- 



