PREFACE V 



should be * first undertaken. This is an introduction to 

 an elementary knowledge of animal structure, function, 

 and development. It consists of practical exercises in 

 the laboratory, each followed by a recitation in which the 

 significance of the facts already observed is pointed out. 

 The general principles of zoology are thus defined on a 

 basis of observed facts. 



Part II is devoted to a consideration of the principal 

 branches of the animal kingdom ; it deals with t system- 

 atic zoology. In each branch one or more examples 

 are chosen to serve as types. The most important struc- 

 tural features of these examples are studied, by dissection, 

 in the laboratory. The directions for these dissections 

 consist of technical instructions for dissecting, the calling 

 attention to and naming of principal parts, together with 

 questions and demands intended to call for independent 

 work on the part of the student. The directions follow 

 the actual course of the dissection instead of being ar- 

 ranged according to systems of organs, and are intended 

 for the orientation of the student and not to be in them- 

 selves expositions of the anatomy of the types. The 

 condensation of these directions is made more feasible by 

 the presence of anatomical plates (drawn directly from 

 dissections). Following the account of the dissection of 

 the type are brief notes on its life-history and habits. 



* This is true if a strictly logical treatment of the subject is held to. As 

 a matter of fact, it is often of advantage to begin with, or at least to take vip 

 from the beginning in connection with the indoor work, some field-work, 

 such as the collecting and classifying of insects and the observation of 

 their metamorphosis. As most schools begin work in the fall, advantage 

 must be taken of the favorable opportunities for field-work at the beginning 

 of the year. These opportunities are of course much less favorable in the 

 winter. 



f The classification of animals used in this book is that adopted in 

 Parker and Haswell's " Text-book of Zoology " (2 vols., 1897, Macmillan 

 Co.). Exception is made in the case of the worms, which are considered 

 as a single branch, Vermes, instead of as several distinct branches. 



