viii PREFACE 



tnose who have once learnt this lesson have thereby obtained possession 

 of a key to knowledge that will fit many locks and disclose the secrets of 

 many mysteries. 



Many teachers fail with their students from various causes, and thus 

 Nature Study itself has undeservedly suffered in reputation. I am here 

 only concerned with one of these causes, it consists in the ignorance of the 

 subject. As in other branches of study, the teacher ought to be ahead of 

 his pupils, although he still must ever remain himself a learner. One of 

 the main objects that has been kept in view during the preparation of 

 these volumes has been to place the necessary information in such a form 

 as to be accessible to the teacher. Of course, finality is not aimed at, for 

 the subject itself is infinite, and the perusal neither of this nor of any other 

 book can of itself make a competent teacher of any one unless he is pre- 

 pared to do his own part, and will observe and study the natural objects 

 around him at first hand. 



What it is hoped to accomplish is to render the way of setting about 

 the work more easy, by putting at the disposal of all who are interested in 

 nature reliable information not hitherto available in a sufficiently accessible 

 form. That the book will escape criticism is neither to be expected nor 

 desired. The field itself is so immense that omissions must necessarily 

 occur, and the method of treatment that has, after mature consideration, 

 been adopted, naturally involves apparent duplication in some instance. 

 These difficulties are inherent in the subject, and perhaps the utility of the 

 work as a whole will not greatly suffer thereby. But at least it is hoped 

 that it may be found helpful to teachers, and interesting to that consider- 

 able body of men and women who take a keen interest in the wonders of 

 nature that everywhere surround us. 



It is a pleasant duty to acknowledge the helpful suggestions which have 

 been received from numerous friends and colleagues, and in this relation 

 special thanks are due to Professor Hickson, F.R.S., for his valuable aid and 

 advice during the critical period while the general plan of the work was 

 under consideration. To Miss Kate Hall and to Mr. H. E. Turner, the 

 Treasurer and Secretary respectively of the School Nature Study Union, 

 I am greatly indebted for material assistance in drawing up the scheme of 

 the book, and also during the subsequent stages of its preparation. 



J. BRETLAND FARMER. 



IMPERIAL COLLEGE OF 



SCIENCE AND TECHNOLOGY. 



