28 DARWINISM AND THE PROBLEMS OF LIFE 



the same rate. While the fox has, on the average, four 

 or five young in a year, the hare has eight to ten young 

 yearly, in about five casts, and the mouse as many as 

 thirty. These figures are far surpassed by the fishes ; 

 the carp, for instance, discharges 3,700,000 eggs. But 

 the highest number is found in intestinal worms. We 

 learn with astonishment that the maw-worm produces 

 64,000,000, and the tape- worm 100,000,000, eggs. 



If we now cast a glance at the life of these animals, 

 we find that their fertility is directly related to their 

 peril. The fox has few enemies, the hare incomparably 

 more, and the mouse is, so to say, the piece de 

 resistance of all our flesh-eating animals and birds. 

 The eggs of fishes are much relished as food by many 

 aquatic animals, and the sluggish, defenceless carp only 

 too often falls a victim to the predatory fishes. Much 

 nimbler is the trout, which has also less enemies to 

 fear in its stream, and so only produces 600 eggs 

 a year. 



But there are other agencies besides enemies that 

 decimate a species. The young foxes pass their early 

 days in a warm and sheltering structure ; much worse 

 is the lot of the hares, which are laid on the bare 

 ground, so that the first arrivals, in the middle of 

 March, nearly always perish ; and the ova of fishes 

 are exposed to all kinds of accidents, as they are 

 very easily washed away or dried up. Remember, too, 

 the difficulties that the egg of the cattle tape-worm 

 encounters before it can become itself a sexually mature 

 animal ! First it has to be ejected in the human 

 faeces, and then it must be licked up by a cow, in the 



