PREFACE TO THE FIRST EDITION 



These directions are a revision and extension of publications by 

 the senior author in 1912 and 1913, and by Curtis and Dodds in 1919. 

 Beginning as printed outlines intended only for use in the University 

 of Missouri, they have come into use in a number of other institutions, 

 and it now seems desirable to provide for more general distribution. 

 The present edition is, therefore, an outcome of some twenty years' 

 development of the introductory course in Zoology at the University 

 of Missouri. It is the result of progressive experimentation in both 

 form and content. The authors know it "works" with underclass 

 students in such an institution, because it is the product of so much 

 experience, not only their own but also that of their colleagues and 

 assistants, who have contributed to each revision. 



The course, as given at the University of Missouri, occupies one 

 semester and consists of three two-hour laboratory periods and two 

 one-hour lecture periods with time for quizzes taken from both. This 

 is, of course, woefully inadequate for a well-rounded introduction to 

 Zoology, but is perhaps as much as can be expected where students in 

 the College of Arts and Science are expected to meet a similar require- 

 ment in physical science. Obviously, the present volume includes more 

 than can be undertaken within these limits. It has been made more 

 comprehensive, because the authors have often found it desirable to 

 vary the content in their own laboratory work and because a publica- 

 tion for general use may properly include more than the minimum 

 needs of a single institution. 



The course at Missouri is required, as an alternate to Botany, in 

 the Arts College, and also for premedical and agricultural students, 

 since it has been the opinion of the faculties concerned that the course 

 as given satisfied both the cultural and the professional requirements. 

 Because the authors' own conviction is thus supported by that of their 

 colleagues, they feel that the work outlined is suitable for these three 

 groups of students to whom Zoology is most commonly offered. 

 Specialization is obviously desirable in later courses, but the first 

 course should be sufficiently general to meet all needs. Because Gen- 

 eral Zoology is given as an underclass subject at Missouri, these di- 

 rections are adapted to underclassmen, but they are believed to be 



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