A NATURALIST IN BRAZIL 



fill themselves to repletion, for which reason the young fish prefer 

 to swim in shallow water, where the large predatory fish cannot 

 get at them. 



Even in the water the economy of Nature begins with the green 

 plants. It is not, however, the larger aquatic plants which constitute 

 the first form of nourishment, but the so-called algae, tiny green 

 granules which float in the water and multiply endlessly by division. 

 They are devoured by microscopically small, primitive animal 

 forms, and also by tiny Crustacea, the size of a pin's head, which, 

 with the help of two swimming-legs, hop up and down in the 

 water, and are therefore called "water-fleas." On these little Crustacea 

 many of the aquatic insects live, and they form the nourishment of 

 small fry, and even the larger fish devour them, and in the sea 

 even the greatest of aquatic animals, the whale, who opens his 

 mouth, takes in water, and then expels it through the sieve formed 

 by his whalebone "beard," so that a Uving broth of all the little 

 floating creatures remains in his mouth, and is swallowed. To cope 

 with such losses the water-fleas and their marine relatives have to 

 multiply at a simply enormous rate, and in order to make this 

 possible Nature has renounced one of her principles. The small 

 Crustacea reproduce themselves without males. Females are produced, 

 which lay eggs, from which more females emerge, although the 

 eggs are not fertilized. The numbers of offspring thus produced 

 may best be envisaged if we think of the old story of the inventor 

 of the game of chess, who asked, as his reward, that a grain of 

 wheat should be laid on the first square of the board, 2 on the 

 second square, 4 on the third, and 8, 16, 32 on the succeeding 

 squares — in short, the number was to be doubled for every square. 

 It appeared, on calculation, that all the corn in the world would 

 have been too little to pay him. For that matter, Nature has 

 employed this method of "virgin procreation" or parthenogenesis 

 in the case of other species — for example, some of the larger Crustacea, 

 the Gall-wasps, and the Plant-lice. In all these creatures males 

 appear only at certain appointed periods, when they have to fertilize 

 special eggs which take longer to hatch. 



Again, the insects which afford nourishment for a number of 

 different creatures multiply very rapidly. But among them are 

 many species which have adopted the other means of maintaining 

 the species. One of the most marvellous creatures in Brazil is the 

 Splendid Phanaeus, a Scarabaeid. How amazed I was when I first 

 saw the insect sitting on a leaf beside the lake of Dos Irmaos in 

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