IV PREFACE 



not depend upon any others. The teacher is thus enabled to 

 give his class such dissections as he wishes and is not compelled 

 to adopt the entire series in order to have his course complete. 

 In my own classes, I vary the order of the dissections from 

 year to year and never go through the entire course. I even 

 occasionally begin the course with the Protozoa and work 

 upward to the higher animals; but I do not consider this 

 usually so profitable a method of procedure for the pupil as 

 the one herein recommended. 



An important feature of the plan of this course has been 

 adopted, in a somewhat different form, from Huxley and 

 Martin's " Practical Biology " and Marshall and Hurst's " Prac- 

 tical Zoology." It is to give the student such practical directions 

 that he can go on with his work intelligently and profitably 

 without having an instructor constantly at his elbow. It has 

 been my experience that far too much of the time of the average 

 youthful student is often wasted in the laboratory because the 

 instructor does not happen to be at hand at critical times to 

 direct his work. The student will often do the work wrong 

 in consequence, or perhaps he will not do anything at all ; in 

 either case his time is wasted and perhaps his material spoiled. 



In most of the dissections the directions are so arranged that 

 the student can complete the study with a single specimen, and 

 the order in which the different systems of organs are taken up 

 in each dissection is made dependent upon this feature. The 

 necessity of practicing economy of material is thus inculcated, 

 and the habit is acquired of studying and handling each 

 specimen with care and judgment. 



I have been fortunate in procuring the cooperation of a num- 

 ber of well-known teachers in the revision of the proofs, with 

 the aid of whom I have sought to eliminate errors so far as 

 possible. Portions of the proofs have been read critically by 



