PREFACE vii 



the truth of the statements made. There is of necessity much that 

 requires more difficult and lengthy work than is possible in the 

 time available for class work, since many of the most fundamental 

 facts could only be discovered by methods involving the greatest 

 accuracy in measurement. 



The instructions as to experimental work are intended to assist 

 the teacher as much as the student. As already remarked, much 

 must be left to individual discretion. Probably instructive experi- 

 ments will occur to the teacher in addition to those given, and I shall 

 be very grateful for suggestions to be included in a future edition. 

 There are doubtless many shortcomings in this manual. Those 

 statements in the text which are capable of experimental illustra- 

 tion are marked with the letter E, and the page of the " Practical 

 Work " on which instructions are given. 



It seemed scarcely possible to add summaries to the chapters, 

 as in my larger book, for the reason that all the matter contained 

 in so small a space is of nearly equal importance, and a summary 

 would have been almost as long as the chapter itself. It would also 

 tend to encourage what I wish most to avoid, namely, any kind of 

 merely learning by heart. The student may find it profitable to 

 make abstracts for himself. 



Structural facts, whether anatomical, histological, or chemical, 

 are not given with more minuteness than necessary to understand 

 the mode of action of the organs they apply to, so far as it is known. 

 If further description is thought useful, such books as Quain's 

 " Anatomy," Schafer's " Essentials of Histology," and Plimmer's 

 " Practical Organic and Bio-Chemistry," may be consulted. 



The best way in which the present book could be used would 

 be for the teacher to take it as a suggestion of what the author 

 regards as the fundamentally important things to be taught, and 

 to describe them to the student in his own words. The student 

 may use the book to remind him of what he has been taught, or 

 to obtain a different way of looking at the phenomena. In this 

 way, that most pernicious habit of learning a subject, already 

 alluded to, may be avoided, to some extent at least. The com- 

 mitting to memory a mass of statements without understanding 

 their relation to one another, or even what they mean, cannot be 

 too carefully guarded against. It is of no value whatever, either 

 as a means of education or for future use. 



