SALPA IN ITS RELATION TO THE EVOLUTION 

 OF LIFE. By W. K. BROOKS. 



Salpa is distinctively a pelagic animal, adapted by its whole 

 structure for a free existence, and for life at the expense of the 

 micro-organisms in the water of the ocean. 



To understand its position and significance in the economy of 

 nature, we must have before us the broad outlines, at least, of a 

 picture of the conditions under which oceanic life has been evolved. 



I believe that the history of the evolution of salpa, as told by 

 its embryology, is most suggestive and important, and that it 

 contributes to the solution of some of the most profound and 

 fundamental problems of biology, and brings us into conflict with 

 some of the most favorite dicta of modern morphology. I shall 

 therefore devote considerable space to a review of certain familiar 

 features of ocean life, in order that I may present in this way my 

 view of the significance of the phylogeny of salpa, in its bearing 

 upon the first principles of morphology. 



Contrast between Terrestrial Life and Marine Life. 



In a picture of the land, the mind calls up a vast expanse of 

 verdure, broken only by water, and stretching through forest and 

 meadow from high up on the mountains, over hills and valleys 

 and plains, down to the sea. 



Our picture of the ocean is an empty waste, stretching on and 

 on with no break in the monotony, except, at long intervals, a 

 floating tuft of sargassum, or a flying fish, or a wandering sea-bird, 

 and we never think of the ocean as the home of vegetable life. 



It contains plant-like animals, " zoophytes," in abundance, but 

 while they resemble plants or flowers in form and color, and in 

 their mode of growth, they are true animals and not plants. 



At Nassau, in the Bahama Islands, the visitor is taken in a 

 small boat, with windows of plate glass set in the bottom, to visit 



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