74 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
weirs for herring at Grand Manan. T[astening on the exterior, they eat 
off the bark in circular spots. 
There is, therefore, no difficulty whatever in establishing the exist- 
ence of vegetable matter in the sea in sufficient quantity to serve as the 
basis for the stupendous mass of animal food derived from it. 
Starting thus from the vegetable kingdom the chain of succession 
of animal life furnishes in one or other of its links food to all. the ani- 
mals of the sea, in the process of such assimilation enormous numbers 
of distinct organisms being consumed for tlie support of a single indi- 
vidual. Nor is there any definite ratio between the size of the food 
used and that of the animal raised upon it, since the baleen or bone 
whales are believed to live almost entirely upon shrimps, floating mol- 
lusks, and upon the smaller fish whenever they can be obtained in suf- 
ficiently large schools. It is well known that herring are devoured in 
multitudes by whales, such as the finback, &e. 
Sixty thousand copepods (Temora longicornis), by actual count, have 
been taken from the stomach of a single herring, while many thousands 
of herring have been taken from the similar receptacle of the whale, 
which shows that this miscroscopic shrimp may be regarded as one chief 
source of the subsistence of the whale—another case of the relation 
between the infinitely small and the infinitely great. 
Some fishes are believed to feed very largely upon the organic mud 
of the sea-bottom, this of course being rich in some of the smaller forms 
of animals and the diatoms. The examination of stomachs of large 
numbers of the common menhaden, by Professor Verrill, revealed no 
other substances than the mud in question; the fish being provided with 
very thick, muscular walls to its stomach, a so-called gizzard, for the 
special purpose of utilizing it. The Dorosoma, or gizzard shad, of the 
rivers of the Atlantic coast, has also a similar provision. 
A favorite implement of the naturalist is-that called the towing-net. 
This is simply a bag of gauze, the mouth of which is held open by a 
ring or brass frame, which is towed behind a boat or vessel so as to take 
a skimming of the surface of the water. This can never be used in any 
part of the ocean without very soon obtaining a greater or less number 
of the minute animal organisms, such as the adult shrimp, the larval 
stages of certain crabs, embryos of mussels and other mollusks, and 
small fishes. 
Around floating sea-weed in mid-ocean are always congregated great 
swarms of minute animals. The presence of whales, dolphins, albicores, 
and other species of animals in mid-ocean also proves the occurrence of 
food in vast quantities; as although all these species may not them- 
selves devour the lower order of animals, they yet feed upon fishes 
which do find their sustenance therein. 
It is not probable that any fish feed directly upon purely ingrmee 
matter. It is through plants that mineral substances of any kind are in- 
troduced into the system, especially that which is required for the for- 
mation of bone. 
