UNIVERSITY 

 ^ or 



PREFACE 



THE main object of this volume is to set forth the 

 natural history of those animals which usually serve 

 as types of animal structure in elementary courses of 

 zoology. The smaller of these have been omitted, and 

 only those whose habits and gross structure can be observed 

 without the assistance of a microscope have been discussed. 

 The Dragonfly and Wasp, as a rule, find no place in the 

 courses to which allusion has been made. They are here 

 introduced, partly to bring forward the phenomena of 

 metamorphosis, which is not to be found in the Cockroach, 

 and partly owing to the interesting nature of their life- 

 histories. 



Sixteen years' experience of teaching zoology has con- 

 vinced me that we have been too closely wedded to 

 structure and have wrongly divorced function from our 

 elementary courses of instruction. Structure alone is 

 very liable to become dry bones in very deed, and con- 

 sequently to fail to attract that interest without which 

 good work is almost impossible. It has been my endeavour 

 throughout this book to present each animal to the reader 

 as a living thing, a machine of whose wonderful parts and 

 workings we have obtained some little knowledge, but 

 concerning which there is yet much to be ascertained. In 

 the hope that a desire for further knowledge may be 

 kindled in the minds of some of those into whose hands 



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