A NATURALIST IN BRAZIL 



to the glass above the surface of the water. When they fall back we 

 see that ten or fifteen eggs are adhering to the glass, being held 

 there by a mass of transparent slime. Now the male stations himself 

 beneath the eggs, and every half hour or so he sprinkles them with 

 his tail-fin. 



Like the Pipa, the Flat-headed Catfish (Fig, 21) carries its eggs 

 upon its body. It first lays them on the river-bed, and then rubs 

 them with its belly, which is covered with cup-shaped cells, and in 

 these the eggs are caught and held fast. It seems that in this species 

 the eggs are actually nourished by the blood of the parent ; a state 

 of things reminiscent of the mammals. 



In the case of the Fishes, as in that of the Frogs, 

 we are able to verify the principle stated in Chapter X : 

 namely, that equilibrium is maintained either by in- 

 creased fertility or by greater security. The further 

 parental care is developed, the better it assures the 

 survival of eggs and young, and the fewer eggs are 

 required to secure the continuance of the species. We 

 see, accordingly, that when there is greater parental 

 care the number of the eggs is diminished, while the 

 size of the individual increases. If the Fyrrhulina lays 

 Fig. 21.— Flat- ^5*^ ^ggs, the "Mouth-hatchers" 60, and those Catfish 

 headed Cat- which guard their brood still fewer, while the Carp 

 fish(Aspredo ig^yg ^oo,ooo, the Halibut 3,000,000, and the Cod 



laevis) with , it n 1 



eggsonbellv 95^00,000, these enormously disparate figures show 



{After Wy- how finely Nature can adjust the coefficient of 



tnann, re- increase, and how, when it is necessary to cover the 



^ monstrous losses of a species unremittingly persecuted, 



from the egg to the adult form, she takes no account of numbers. 



A stupendous variety of devices for ensuring the survival of the 

 young, and a steady gradation, from the most inconsiderable to the 

 most ingenious achievements, are to be found in the insect kingdom. 

 These matters must awake interest in even the most sophisticated, 

 and since the insects are the most numerous of all the living creatures, 

 we have here a province by which anyone may approach the study 

 of natural history, and constantly avoid the danger of boredom. 

 For example, the inhabitant of Rio might go to Alto Boa Vista one 

 fine summer morning, and wander along the footpath to the peak 

 of Tijuca; or he might cross the Bay, and stroll up the hills of the 

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