1:38 LAWS OF MULTIPLICATION. 



puppies at first, than afterwards/' According to Burdacli, 

 as quoted by Dr. Duncan, " the elk, the bear, &c., have at 

 , first only a single young one, then they come to have most 

 frequently two, and at last again only one. The young 

 hamster produces onl}^ from three to six young ones, whilat 

 that of a more advanced age produces from eight to sixteen. 

 The same is true of the pig.*' It is remarked by Buffon that 

 when a sow of less than a jeav old has young, the number of 

 the litter is small, and its members are feeble and even im- 

 perfect. Here we have evidence that in animals growth 

 checks sexual genesis. And then, conversely, we have 

 evidence that sexual genesis checks growth. It is well 

 known to breeders that if a filly is allowed to bear a foal, 

 she is thereby prevented from reaching her proper size. And 

 a like loss of perfection as an individual, is suffered by a 

 cow that breeds too earl}^ 



§ 342. Notwithstanding the way in w^hich the inverse 

 variation of growth and sexual genesis is complicated with 

 other relations, its existence is thus, I think, sufficiently mani- 

 fest. Individually, many of the foregoing instances are open 

 to criticism, and have to be taken with qualifications ; but 

 w^hen looked at in the mass, their meaning is beyond doubt. 

 Comparisons between the largest with the smallest types, 

 whether ves^etal or animal, vield results that are unmis- 

 takeable. On the one hand, remembering the fact that 

 during its centuries of life an Oak does not produce as many 

 acorns as a Fungus does spores in a single night, we see that 

 the Fungus has a fertility exceeding that of the Oak in a de- 

 gree literally bej^ond our powers of calculation or imagina- 

 tion. When, on the other hand, taking a microscopic 

 protophj^te which has millions of desceildants in a few daj^s, 

 we ask how many such would be required to build up the 

 forest tree that is j^ears before it drops a seed, we are met 

 by a parallel difficulty in conceiving the number, if not in 

 setting it down. Similarh^, if we turn from the minute and 



