INTRODUCTORY NOTE 



This laboratory manual was prepared for the dass in elementary zoology in 

 the University of Chicago, and has been used in this course for some time. In 

 the three months' time allotted for the course, nearly all of the work given in 

 sections I to XII, inclusive, is completed, with the exception of the muscular and 

 skeletal systems of the frog. The remaining sections have been added for pub- 

 lication because they seem to the author to be essential for a complete course in 

 general zoology. The directions have been written entirely from the material, 

 although, of course, many textbooks have been consulted throughout. An 

 attempt has been made, not merely to give explicit directions for the study of the 

 material, but also to point out the relation of each section of the work to the 

 general principles of biology and to make clear why each particular kind of 

 material has been selected. The sections are given, naturally, in the order 

 which the author thinks most logical, but they can be shifted at the will of the 

 instructor. Our experience, extending over many years of trial of both methods, 

 has shown that starting the course with the dissection of a complex animal is 

 much more satisfactory than introducing the student at the start to the lower 

 invertebrates, for the reason that the simplicity of the latter cannot be appre- 

 ciated and understood except with reference to completely differentiated animals. 

 Any vertebrate would serve the purpose, but the arthropods are in general unsuit- 

 able because they introduce the problem of heteronomous segmentation for which 

 the beginner is not prepared. Many teachers will object that the instructions 

 are too detailed and that it is better pedagogy to compel the student to work 

 out things by himself; but the large amount of ground which must be covered 

 in a relatively short time and the impossibility of providing sufficient laboratory 

 assistants for the large classes with which we have to deal necessitate detailed 

 directions. The student pursuing the modern college curriculum simply does 

 not have time to carry out an original investigation on the anatomy of an animal; 

 and unless he is provided with detailed directions, instructors and assistants are 

 overburdened with the task of explaining to him what he is looking at, what to 

 do next, etc. There is no reason why this extra work cannot be avoided by 

 including these explanations in the manual. 



