THE 



AMERICAN NATURALIST 



Vol. LVI. November-December, 1922 No. 647 



THE PROGRESSION OF LIFE IN THE SEA^ 

 DR. E. J. ALLEN, F.R.S. 



The method we usually follow in the ordinary course 

 of zoological work is to make first, with the unaided eye, 

 a general examination of the animal that interests us, 

 and then study in detail its separate parts with a simple 

 lens, with a low power of the microscope, with gradually 

 increasing powers, until, finally, minute portions are ex- 

 amined with the highest oil-immersion lens. The suc- 

 cessful research worker is generally one who, whilst car- 

 rying to the utmost limit he can achieve his search into 

 detail, maintains as by instinct a true sense of proportion 

 and holds firmly to the idea of the organism as a whole. 



In discussing the living organisms of the sea I shall 

 try to follow a similar plan, thinking of the life of the 

 sea as a whole, built up of individual plants and animals, 

 each in intimate relation with its surroundings, and all 

 interdependent among themselves. But even this is not 

 enough, for we must take still a wider view and keep in 

 mind not only the life of the waters, but that also of the 

 land and of the air, for both, as we shall see, have a bear- 

 ing on our theme. Deep oceans, coastal waters, shallow 

 seas, rivers and lakes, continents and islands, all play 

 their part in one scheme of organic life— life which had, 

 it seems, one origin, and, notwithstanding migrations and 

 transmigrations from water to land, from land to air, and 

 from land and air back again to the water, remains one 

 closely interrelated whole. 



1 Address of tlio President of the Section of Zoolc^- of tlic British As- 

 481 



