PREFACE 



Although prefaces are commonly forgotten, if indeed they are 

 read by teachers, it seems that one must say something regarding 

 the origin and nature of a new textbook, particularly in a field 

 that is already well occupied. The present volume is the outcome 

 of a work projected some years ago by the senior author as a formal 

 organization of the course in General Zoology that has been devel- 

 oped at the University of Missouri during the past twenty-five 

 years. Historically, it is the descendant of the course in General 

 Biology that was introduced at the Johns Hopkins University by 

 Huxley's student, Newell Martin, and later developed in that 

 institution by E. A. Andrews. From Johns Hopkins and also 

 from its original source in Huxley and later teachers in England, 

 like T. J. and W. N. Parker, this early attempt to teach the prin- 

 ciples of biological science has influenced instruction in many 

 American institutions. 



At the University of Missouri the course began as General 

 Biology, but was restricted to the field of Zoology with the estab- 

 lishment of a separate department of Botany. The essential fea- 

 ture of this instruction in General Zoology is that a limited number 

 of animals are selected to illustrate certain biological principles 

 and only incidentally as representatives of particular phyla. 

 This is in contrast with what may be called the " phylum " 

 scheme of instruction, which has been widely prevalent during the 

 past twenty years and is represented by well-known textbooks. 

 The later form of instruction seems to have originated in the old- 

 time courses in Natural History, represented by books like Ten- 

 ney's "Manual of Zoology," and to have been transformed into 

 modern garb through the influence of Louis Agassiz and his 

 students. In both the "principles" and the "phylum" courses, 

 the method of instruction by "types" has been utihzed; but in 

 one case the type illustrates principles, while in the other it shows 

 the morphology and physiology typical of a given phylum. 



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