360 THE POPULAR SCIENCE MONTHLY. 



influence is fundamentally different from all the natural dangers 

 to which sea-fishes are exposed, since it is modern or recent, and 

 has, therefore, failed to be recognized and provided against during 

 the evolution of these animals. In this sense man's influence is. 

 unnatural, while all other dangers are natural. The danger from 

 man is not only modern, but also totally anomalous in the rapid- 

 ity of its approach. It has not grown up gradually and imper- 

 ceptibly, but has swept over the entire ocean with a speed which 

 leaves no chance for the production of compensating adjustments, 

 by the slow process of selection. If it were to remain without 

 change, or were to change very slowly, there can be no doubt that 

 all the species which were not quickly destroyed would ultimately 

 be brought into adjustment, and would from that time on be able 

 to resist ; but what animal can become adjusted to an enemy who 

 is able, in less than a generation, to increase his power by such 

 inventions as th« steamboat, the electric light, and the dynamite 

 bomb ? To marine food-fishes man is a catastrophe, not a natural 

 enemy, and the natural methods of maintaining the harmony be- 

 tween oceanic animals and the slow geologic changes of the ocean 

 bottom are of no avail against him. 



A study of the destructive forces of nature shows that man is 

 peculiar in other all-essential particulars. It is a well-known fact 

 that of all the marine animals which fall a prey to enemies, or be- 

 come the victims of accidents and diseases, all but an infinitesimal 

 percentage are destroyed during infancy or youth. As soon as 

 the eggs of a fish are laid, the process of decimation begins, and it 

 is initiated on a scale which would quickly sweep the species out 

 of existence if it lasted long ; but, fortunately, it does not, and each 

 day in the life of a young fish brings with it an enormous increase 

 in the chance for a long life. 



During the early stages of development the young fish is to- 

 tally defenseless, and at the mercy of enemies and accidents ; and, 

 although each pelagic fish lays enormous numbers of eggs, not 

 a single one could escape if the embryonic period were long. 

 Natural selection has been constantly acting for untold ages to 

 shorten it, however, for in each generation those eggs which de- 

 veloped most rapidly have most frequently escaped destruction ; 

 and as the fishes which hatched from these precocious eggs have 

 inherited a tendency to produce similar eggs, the embryonic life 

 has gradually grown short, and most pelagic eggs now develop so 

 rapidly that it is not unusual for them to hatch within twenty- 

 four hours after they are fertilized. After they are hatched the 

 transparency and activity of the little fishes add greatly to their 

 safety, although each school of young fishes is constantly encom- 

 passed on all sides by a host of enemies. I have found, by watch- 

 ing for an hour from the end of a wharf a school of some eight 



