1096 Growth, its Conditions and Variations. [November 
be obtained by great exertion. But unlike land animals the 
largest birds are the Carnivora, since the food to which they are 
adapted is far more abundant than can be obtained by the peck- 
ing fruit-eating, or the insectivorous birds, But the largest of all 
birds are those that have lost the habit of flying, and with it the 
necessary muscular waste. And of these land birds the largest 
known to us were those sluggish inhabitants of the Pacifc 
‘islands, whose habitat was untenanted by large Carnivora, and 
their food abundant, so that they did not need the activity of the 
desert-living ostrich. 
If now we consider water animals, the considerations here 
taken receive a remarkable exemplification in the whale, with i 
_bulk so greatly in excess of that of any land animal. An exami- 
nation of the structure of the great Greenland whale would m 
lead to this conclusion. It has lost all the weapons on which its 
land kindred depend. Its teeth have vanished. Its hind limbs 
have disappeared. Its fore ones are only used for swimming. 
Its food-getting powers seem singularly reduced, while the food 
upon which it depends consists of minute, almost microscopi 
animals. Thus a natural conclusion would be that the whale 
should be of small bulk instead of gaining such monstrous pre 
portions. But on the other hand its food is supersint 
quantity, and is utterly defenceless against its huge foe. 
. uld be 
whale needs no weapons to capture its food. These wo dy 
useless and have been lost. All it needs is to rush set 
through the water with open mouth and swallow the food w 5 
it thus collects in great masses. Intelligence would be useless 
it, and is greatly lacking. Its muscular waste is compti 
small, since swift motion through the water needs far less > 
tion than on the land. It has no foes whom it endeavors 
escape by flight. Thus there is nothing to hinder its a 
inordinate bulk. In this whale, and related species of pape 
general habits, the powers of growth attain their ultimate | 
opment, | 
j; 
The same consideration applies to the great sperm w 
which is adapted, indeed, to a food of different hae 
seems to obtain as abundant a supply with as little exertion. 
remaining water mammals are smaller. They trust to 0%" | 
is less abundant, and which needs more exertion to pane itis 
seals cannot obtain their fish food without great agility, 
