£38 LAWS OF MULTIPLICATION. 



puppies at first, than afterwards." According to Burdach, 

 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 only from three to six young ones, whilst 

 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 year 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 hy a 

 cow that breeds too early. 



§ 342. Notwithstanding the way in which 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 

 when looked at in the mass, their meaning is beyond doubt. 

 Comparisons between the largest with the smallest types, 

 whether vegetal or animal, yield 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 

 protophyte which has millions of descendants in a few da} T s, 

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

 forest tree that is years before it drops a seed, we are met 

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

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



