THE BASIS OF LIFE IN THE SEA 153 



These rough calculations are sufficient to show that the 

 pastures of the sea must be very rich, for not only do the marine 

 pastures support numerous whales of all sizes, but in addition 

 various large sharks, a number over 40 and one over 50, and 

 said to reach 70, feet in length, and other huge fishes which are 

 not eaten by whales and therefore compete with them for the 

 food supply. And then there are the seals and the sea-birds 

 and hosts of bottom hving animals in many places forming 

 living carpets for miles and miles, all browsing, so to speak, 

 directly, or mostly indirectly, on the same pastures. 



It has been said that the marine pastures are richer than 

 the pastures of the land, and on occasion this certainly seems 

 true; but close comparison between the two is difficult. In 

 the first place sea animals require much less nutriment than 

 those on land so that comparison bulk for bulk between the 

 two means little. Furthermore many whales and many of the 

 larger fishes, like the mackerel and the herring, are migratory 

 creatures, wandering regularly or more or less irregularly from 

 place to place. On land the growth of vegetation with us 

 ceases in the winter, and in the tropics is much reduced in 

 the dry season; nowhere is it uniform throughout the year. In 

 the sea the growth of vegetation also varies at different times 

 or seasons quite as much as on the land. 



On land all vegetation grows on the ground, or on some sup- 

 port fixed to the ground, and all animals live on or in the 

 ground or among the plants growing upon it. Such animals 

 as traverse the air do so only as a means of getting from place 

 to place or, a very few, to feed upon others so engaged. The 

 air, for all practical purposes, is a sterile medium. Potentially, 

 however, conditions are quite otherwise. 



In the city of Caracas I was always greatly interested by the 

 sight of festoons of plants, especially "wild pine-apples" or 

 bromelias, growing on the electric light cables high in air and 

 nourished only by substances extracted from the air. What 

 does this signify? It proclaims the fact that wherever a plant 

 can find support it can grow in the air just as well as on the 



