2OO THE MEANING OF EVOLUTION 



sweet. I have seen a male sit upon a clump of grass 

 and utter his love call. Before he had been singing 

 for more than half a minute three females hastened 

 toward him from a distance of perhaps twenty feet. 

 Each seemed anxious to reach as promptly as pos- 

 sible the creature whose voice had proved so attrac- 

 tive. When the mating comes, the female discharges 

 a series of small shotlike eggs which are encased in 

 a very tenacious mucous. While they are being de- 

 posited the male fertilizes them. No sooner have the 

 eggs, fertilized by the sperm cells, reached the water 

 than the mucous at once begins to swell. The result 

 is that eggs appear encased in two slender strings of 

 jelly, each having a diameter about that of a lead 

 pencil. At intervals of not more than half an inch 

 the shotlike eggs may be seen. The mother toad, in 

 laying these eggs, moves about rather restlessly in 

 the water. By this means she succeeds in wrapping 

 the strings about the grass and sticks of the pool. 

 This will hold them quite safely even against a con- 

 siderable current of water, should the stream rise and 

 flood the side pools in which the eggs are laid. With 

 this amount of care, however, the attention of both 

 parents to the young entirely ceases. They are now 

 abandoned to the chances of a fortune to them ex- 

 ceedingly unkind. A toad will lay about five hundred 

 eggs. It is evident that on the average only two of 



