CHAP. IX. | I HE BALANCE OF LIFE. 71 



Chapter IX. 

 THE BALANCE OF LIFE. 



reature lives beneath r 

 Bui has some dangers ever) day to run," 



Knipe — Nebula to Man. 



tN preceding chapters we have already discussed Reproduction 

 .iml Metamorphosis in insects. Lei us now take the case of an 

 insect laying only two hundred eggs and passing through its life- 

 cycle in one month and consider the possible number of its 

 descendants if all attained maturity. Commencing for convenience 

 sake on 1st January we have one fertilized female which lays 200 

 eggs, all of which hatch and mature by the end of the month ; on 

 the average half of these will be females, each of which will lay 

 200 eggs on 1st February and by the end of February we have 100 X 

 200 = 20,000 mature insects, of which hall again will be females 

 laying between them 10,000 X 200 = 2,000,000 eggs. It would be 

 tedious to follow the increase month by month, but simple calcula- 

 tion shows that by the end of the year the descendants would reach 

 the prodigious total of two trillions (2,000,000,000,000,000,000,000,000) 

 of individuals. The human mind is quite incapable of grasping 

 the significance of such a figure but a few comparisons may assist 

 imagination. If one thousand of tin insects weighed only one 

 ounce, their united weight would be 558,035, 7l8,57I,428'S ton--, and 

 if one thousand measured one cubic inch they would cover an area 

 of almost fifty thousand millions of square miles with a uniform 

 layer one inch deep or would till a space of 7,862,931 cubic miles or 

 a cube measuring 198 mil. n h side. Taking the dry sur- 



face of the whole earth to be fifty-one millions of square miles. 

 they would cover the whole of this to a depth of over eighty-one 

 1, et. 



The case of the insect which we have considered above is by no 

 means extraordinary as regards either the number of eggs deposited 

 or the shortness of the life-cycle and it must also be remembered 

 that we have only considered il of a single individual of one 



species amongst the thousands of different insects found in every 

 square mile in India. 



But, alter reckoning the theoretically possible rate oi met. 

 shown above, let us descend to facts and ask. what will be the 

 actual number of descendants of our imaginary insect which we shall 



