

Field. — Sources of Marine Food 179 



swarm like locusts and a herring bank is almost a solid 

 wall." Goode tells of a school of mackerel which was 

 estimated to contain a million barrels and of another 

 which was a windrow of fish half a mile wide and at 

 least twenty miles long. In the bays and estuaries beds 

 of sea mussels are found containing 6,000 to 8,000 

 bushels to the acre. 



How this vast multitude of animals can be supported 

 in a region apparently destitute of vegetation has been 

 a problem of investigation since the microscope came 

 into use and it is interesting to note that the first serious 

 contribution on the subject was written Oct. 16, 1699, 

 by the old pioneer, Anton van Leeuwenhoek, who ground 

 lenses and made his own microscopes. After observing 

 the minute organisms which he discovered in fresh 

 water by means of his microscope he came to the follow- 

 ing conclusion: "If it be then asked, to what end such 

 exceedingly minute animalcules were created, no answer 

 can readily be given which seems more agreeable to the 

 truth than that, in like manner as we see constantly, 

 that the bigger kinds of fish feed on the smaller; as, for 

 example, that the cod fish preys on the haddock and other 

 smaller kinds of fish ; the haddock again on the whiting ; 

 these on still smaller fishes, and among the rest on 

 shrimps ; and shrimps on still more minute fishes ; and 

 that this gradually prevails among all the kinds of fish; 

 so that, in a word, the smaller are created to be food 

 for the larger. Again, if we consider the nature of our 

 [sea, abounding with fish, yet having nothing at the bot- 

 tom of it save barren sand : stored with various shell- 

 ffish, yet destitute of every green herb; and if we, 

 moreover, lay it down for a truth, that no fish can be 

 supported on water alone, there will not remain a doubt, 

 that the smaller fishes are destined, by nature, to be the 

 subsistence of the larger." It is evident from Leeuwen- 

 hoek's illustrations that his use of the expression 

 "smaller fishes" refers to what we now recognize in 

 general as plankton, which includes both animal and 

 vegetable organisms. 





