68 POPULAR SCIENCE MONTHLY. 



THE FEOG AS PAKENT. 



By Pkofessok E. A. ANDREWS, 



JOHNS HOPKINS UNIVEKSITY. 



IN the life of a common frog or toad we seem to find none ef that 

 altruistic solicitude for the welfare of the helpless younger mem- 

 bers of society, that we so fondly attribute as guide in many of our own 

 actions. In clamorous spring reunions these cold-blooded creatures 

 deposit their eggs in the water and go their way in search of food — not 

 knowing whether some or many of the eggs will run a normal course 

 through tadpole or pollywog states to tailless adults, or fall a prey to 

 hungry ducks, or more insatiable naturalists in search of 'material' for 

 study. 



The naturalists' belief that these Amphibia are closely akin to fish in 

 many ways is borne out in their breeding habits; for, like fish, they have 

 more or less complex 'instincts' that lead the males and females together 

 at the laying season, and then, like fish, they separate till the next 

 period of egg-laying. The eggs, discharged in the water, are fertilized 

 outside the body, and undergo a process of cleavage or cell-multiplica- 

 tion, thus gradually differentiating into active larvas or tadpole? without 

 any care from the parents. The tadpole leads its own independent fish- 

 like life for months or years, till — if not destroyed — the critical period 

 of transformation arrives. This passed, the young frog or toad has 

 only its instincts to guide it in learning the new life and nothing to 

 learn from its parents — unless perchance they may be near enough to 

 endeavor to swallow it alive. 



Yet even here we might fancy some thought for the morrow of the 

 species — the eggs are generally laid in the right place — according to 

 the kind of frog or toad — to have enough water and not too many ene- 

 mies for the young, while the protecting jelly mass about the eggs is 

 often rather carefully fastened to plants or sticks, thus keeping them 

 near the surface of the water and in optimum conditions for hatching. 



But this is not clear until we see some of the extremes to which 

 such prevision for the next generation is carried in certain members 

 of this group. Just as amongst fish there are a few with most remark- 

 able habits — the male stickleback watching and protecting the eggs in 

 his carefully made nest — so, if we look far enough, we find frogs and 

 toads that show most exemplary solicitude for the young. In Europe, 

 Asia, Africa and in South America such curious life-histories are more 

 or less common. 



