1 3 o 



ZOOLOGY 



Ratio be- 

 tween 

 numbers 

 and chance 

 of survival 



3. Why should life thus press against the environ- 

 ment, seeming ever to seek the impossible ? In a cer- 

 tain sense, the hunger of life and the hunger of fire are 

 parallel phenomena, as St. Francis seems to have dimly 

 perceived when he regretted having deprived "brother 

 fire" of the opportunity to consume his coat. There 

 is, however, another point of view. Life cannot extend 

 indefinitely ; everywhere it finds limits to its activities. 

 The 500 seeds of the roadside weed are so many trials, 

 experiments, tickets in the great lottery of the world. 

 It is practically impossible for all to succeed, and conse- 

 quently, were no surplus produced, life would become 

 extinct. By a strange paradox, it becomes necessary 

 to accept failure in order to attain success. Sacrifice is 

 part of the game, and those who fail have played their 

 part. There is actually a definite ratio between the 

 number of offspring and the chances of survival. The 

 scale insect which produces a family of six thousand 

 prospers as a species, but the individual at birth faces 

 fearful odds. We recall the old story of the lion and the 

 fox. The lioness goes forth with her single cub, and 

 meets mother fox with her many children. "Ah," says 

 the fox, " I have a fine family ; I am sorry for you, with 

 only a single cub!" The lioness replies: "I beg you 

 to recall that my child is a lion, yours are only foxes !" 

 Biologically, the lion is quite right. Species which pro- 

 duce few young are those in which the rate of survival 

 is correspondingly high ; one lion is worth several foxes, 

 and thousands of spiders, in this sense. Nevertheless, 

 even the most successful forms of life cannot avoid 

 losses, and were man himself to produce on the average 

 only two children for each pair of parents, our species 

 would vanish from the earth. 



