INTRODUCTION. 



errors or difficulties. All questions asked should be 

 answered in the note-book. 



At various points are questions grouped under the head- 

 ing ' Comparisons.' These questions are based upon the 

 previous laboratory work, and are intended to bring out 

 clearly in the student's mind the essential points of resem- 

 blance and of difference in the forms studied, and the 

 bearings of the facts discovered. Laboratory work trains 

 the powers of observation; the answering of such ques- 

 tions leads to a systematization of knowledge and an 

 exercise of the reasoning powers. The value of any 

 scientific study lies not so much in the number or impor- 

 tance of the facts learned as in seeing the relationships 

 of these facts and the conclusions to be drawn from them. 

 Hence each pupil should be required to hand in answers 

 to these questions and to make the answers as detailed 

 as possible. 



Following each list of comparisons is a reference to 

 the pages where a general account of allied forms and 

 a statement of the principal characteristics of the group 

 may be found, thus giving a completeness to the knowl- 

 edge which otherwise would be utterly lacking. In 

 these general statements there are frequent references to 

 the sections where the student has worked out the point 

 for himself. In this way the work throughout will be 

 based upon the inductive method, and finally the animal 

 kingdom will be comprehended as a whole. 



EQUIPMENT. 



The room used for laboratory purposes should be well 

 lighted and ventilated and should be furnished with 

 running water. There should be receptacles, prefeiably 



