PREFACE ix 



Journal ; " Sea Fisheries " was a Presidential 

 address to The Association of Economic Biolo- 

 gists, and " Grouse Disease " an evening lecture 

 delivered before the Royal Institution. For per- 

 mission to reprint these I owe my thanks to the 

 authorities of the several institutions named 



above. 



A. E. SHIPLEY. 



Christ's College Lodge, 

 Cambridge. 



October, 1916. 



