362 THE POPULAR SCIENCE MONTHLY. 



the species and to keep the area which it inhabits stocked with as 

 many adults as it can support. 



All the natural sources of mortality are thus provided for. As 

 each species is slowly and gradually brought into harmonious 

 adjustment to the conditions of its environment, its birth-rate, 

 like all its other attributes, is regulated and adapted to meet all 

 the natural demands upon it. Now what happens if, after each 

 one of the natural enemies has claimed its victims, a new enemy 

 not provided for by Nature suddenly attacks the few adult surviv- 

 ors which Nature has provided to perpetuate the species ? What 

 happens when the last drop falls into the brimming bucket ? 

 "What happens when the proverbial last straw is put on the load ? 

 It may be quite true that, for each codfish which man catches, the 

 natural enemies destroy a million. That has no bearing on the 

 subject. Nature has provided for the destruction of the million. 

 Before their birth they were destined to premature death. The 

 one was reserved by Nature for another purpose. 



If the destructive influence of man had been gradually brought 

 to bear, and had kept pace with the evolution of the species, nat- 

 ural selection would have provided a remedy, and the birth-rate 

 would have been correspondingly increased ; but this has not been 

 the case ; and, while man might not be able to make any impres- 

 sion on the broad base of the pyramid, we must remember that 

 he does not attack the base, but the pointed apex. The fact that 

 sea-fishes are so enormously prolific is entirely irrelevant. Their 

 high birth-rate is an adjustment to their natural environment, 

 while the influence of man is a new factor which has not been pro- 

 vided against. 



It is difficult to get statistical information regarding marine 

 animals, but there is ample evidence that they may be extermi- 

 nated by man. The Bahama sponge-fishermen complain that they 

 are now compelled to make long voyages and to visit remote banks 

 for sponges which in former years could be gathered in abundance 

 near the seaports. It is well known that, just before the oil from 

 the wells of Pennsylvania came into common use, the sperm- 

 whales had become so scarce that they were in imminent danger 

 of extermination. The scarcity and the high price of sea-fishes 

 in the vicinity of large seaport towns are unquestionable ; and the 

 shore-fisheries of the New England coast, to which Cape Cod owes 

 its name, have been so completely destroyed that, when the Cape 

 Cod fishermen caught, a few months ago, in their nets some of 

 the young codfishes which had been hatched in the Fish Com- 

 mission laboratory at Wood's Holl, they brought them to the 

 naturalists as specimens of a new and unknown species. The 

 destruction of sea-fishes may require many years, but there is no 

 animal on earth large enough to be valuable as human food which 



