PREFACE 



Signs are not wanting that at the present time a revival of 

 interest in Zoology is taking place, and this book is an attempt 

 to help on the movement by pointing out the various lines of study 

 and explaining in simple language the views of modern specialists. 

 Every effort has been made to treat the subject-matter in such 

 a way as to interest the general reader, while at the same time 

 the needs of junior students, amateur naturalists, and teachers of 

 elementary Zoology (including "Nature Knowledge") have been 

 steadily borne in mind. 



All the larger popular books on Zoology which have so far 

 appeared in English take the various animal groups seriatim, a 

 time-honoured plan which is in many ways valuable and useful, 

 but which fails to bring out the complex interrelations that exist 

 between the different groups, the interdependence of animals and 

 plants, and the bearing upon life of chemical and physical con- 

 ditions. A due appreciation of the great complexity of the struggle 

 for existence, and a realization of our comparative ignorance re- 

 garding adaptation of structure to habit, should open innumerable 

 fascinating lines of really scientific study to many amateurs who 

 are at present mere collectors of insects, birds' eggs, or shells. It 

 may, however, be noted that Half-Vols. I and II to some extent 

 meet the needs of those who prefer the old plan, for they review 

 in brief the entire animal kingdom, as a necessary preliminary to 

 the study of the Food of Animals, Animal Defences, &c., which 

 constitute the subject-matter of the remaining volumes. Even in 

 the first two half-volumes, however, comparisons are constantly 

 instituted between different animals and different groups, in illus- 

 tration of general principles. 



