A NATURALIST IN BRAZIL 



In Brazil, then, the naturaUst meets with something surprising 

 at every step; every creature is unHke the creatures that he knows 

 at home, and he is filled with reverence before such an inexhaustible 

 wealth of forms. But he cannot be content with mere amazement ; 

 he longs to understand something of the wealth of species offered by 

 the world about him. And he is struck, in the first place, by two 

 things, and he perceives that they are mutually interdependent; 

 on the one hand, the overwhelming powers of multiplication 

 possessed by animals and plants alike, and on the other, the enor- 

 mously varied conditions of life which this earth affords. 



As a matter of fact, every plant, every animal, could by itself 

 overpopulate the earth. In order to realize this, we have only to 

 calculate the number of the descendants produced by any animal 

 over a series of years — presuming, of course, that all survive and 

 multiply. We shall perceive at once that from the very outset some 

 counteracting factor is necessary. This factor is found in the living 

 substance itself, which is a delicate and mutable mass, and cannot 

 thrive equally in all situations, but must have its special conditions 

 of life : namely, a certain temperature, humidity, nutriment, etc. 

 But the conditions of life are not uniform in all parts of the earth, 

 for the surface of our planet varies greatly in character : it has hot 

 plains and cold mountain peaks, torrid and arctic zones, water and 

 land, light and darkness, and all in innumerable gradations. Even 

 though life is endowed with the urge to propagate itself incessantly, 

 and to fill the whole earth, it must always adapt itself to these 

 different conditions, and vary its form and its characters accordingly. 

 And here we have the first reason for the multiplicity of forms existing 

 in the animal and vegetable worlds. 



Moreover : if we were set the task of filling a chest with stones so 

 completely that the last and tiniest chink was filled up, we could 

 accomplish it only by taking stones of different sizes, down to the 

 finest particles of sand, with which to fill up the remaining spaces. 

 All these stones would have to be most carefully fitted together. 

 But even if this task of meticulous adjustment could be accomplished, 

 what difficulties would arise if the stones all insisted on moving in 

 prescribed orbits ! Here human skill would be utterly baffled. With 

 what reverence, then, should we regard Nature, by whom this 

 problem has been solved ! 



Let us take any tract of woodland, a grassy plain, or a pond : 

 we shall see that to every condition of life which such a fragment 

 of Nature offers some living creature has adapted itself, and that 



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