vi PREFACE TO THE EIGHTH EDITION 



with the brevity of life, tend to sunder things which should be joined,, 

 and in the same measure, the law of ?ction and reaction holding' 

 even in schedules and time tables, to join things which were better 

 apart, it would have seemed to the author even more appropriate 

 to place the exercises at the beginning of the chapters, or best of 

 all to interweave them with the text till the ' phase boundaries r 

 between the two disappeared as far as might be a process which 

 might perhaps often be applied with advantage to the phase- 

 boundaries (of lath and plaster, still more of mental attitude; 

 between lecture - room and laboratory. The book would then- 

 become, if the design could be adequately carried out, a text-book 

 ot physiology, in the perusal of which the student was not permitted 

 to forget for a moment that the value of the so - called ' facts ' 

 described was in the last analysis dependent wholly upon the 

 accuracy of innumerable observations carried out in the laboratory 

 by methods and apparatus with which he had gained, or was gaining, 

 some first - hand acquaintance in his practical work. When a 

 statement in the text is followed by a page reference to the Practical 

 Exercises this is for the precise purpose of reminding the student 

 that the laboratory is the seed-bed of the whole science. Lest he 

 forget this the exercises are not even placed all at the end of the 

 book, still less in a separate volume. 



The question has been sometimes asked whether the methods. 

 and especially the apparatus described in the exercises, will exactly 

 suit most laboratories. They will not, and they ought not to be 

 expected to do so. This is also necessarily true of all laboratory- 

 guides. All must be adapted in some measure not only to the 

 material equipment of any particular laboratory in which they are 

 being used, but quite as much to the ideas and, what is by no means 

 unimportant, to the habits of the teacher. To a certain extent in 

 America a standardization of physiological apparatus for students 

 has been realized, and this has been of considerable benefit to the 

 teaching of physiology. Incividu?! teachers and laboratories have 

 nevertheless gone on developing their own ideas with marked- 

 advantage, and nothing would be less desirable than the uniformity 

 of machine-made physiological teaching, could this be achieved, 

 which luckily, in the nature of things, it cannot be. 



CLEVELAND, 

 April, 1918. 



