PREFACE 



Hitherto, the authors of works deah'ng with the sea-shore 

 have confined themselves almost entirely to describing and 

 classifying the different forms of life occurring between tide- 

 marks. The main idea underlying the present work, on the 

 other hand, is to treat the plants and animals inhabiting the 

 sea-shore from the ecological standpoint : to show, that is, 

 how they interact and, in particular, to demonstrate the 

 influence of the environment upon their structure, functions, 

 habits and general reactions. A knowledge of the external 

 appearance and chief structural features of the commoner 

 species is taken for granted, and the book is addressed more 

 particularly to the serious student of biology. But while, 

 on the one hand, no attempt has been made to shun 

 technicalities, on the other, care has been exercised that 

 they should not be multiplied unnecessarily. Consequently, 

 there should be nothing in the mode of treatment of the 

 work which unfits it for use by the general reader. 



The value of the sea-shore as a biological training ground 

 in general, and as a field for ecological study in particular, 

 is generally recognised. With the exception of the shallow 

 sea, no other area on the globe is so rich in numbers and 

 variety of animal species. The fact that the sea-shore is one 

 of the oldest haunts of life makes it particularly valuable for 

 the study of evolutionary processes. Existence on the sea- 

 shore implies the solution of a number of exceptionally 

 interesting problems ; in particular, the rhythmical and other 

 ailed factors influencing shore organisms are of a nature 

 which is unparalleled elsewhere. Finally, the different 



