300 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
products there was a very comprehensive display of fishes, oysters, 
lobsters, clams, turtles, shrimps, etc., preserved by canning in various 
ways, and by smoking, pickling, and salting. 
The fresh-fish industries were illustrated by casts and engravings of 
the principal food-fishes and by pictures showing the manner of their 
capture. A series of shells of salt and fresh water mollusks commonly 
used for food or bait and a comprehensive collection of edible crusta- 
ceans preserved and mounted were also exhibited. The secondary 
products of the fisheries, also of considerable and increasing value, 
were illustrated as completely as possible. The principal of these are 
glues, fertilizers, oils, and isinglass. 
From the skins of cusk, cod, and other fishes a superior glue is 
manufactured. These skins were formerly thrown away as waste, 
but now, after they have been cooked and the glue extracted, they 
are again used in the manufacture of an excellent fertilizer. Fertilizer 
is also produced from the waste in canning various other species and 
from the residuum of fish oil. The best and most extensively manu- 
factured fish fertilizer is made from the menhaden, which is compara- 
tively valueless as food and is found in great quantities all along the 
Atlantic coast. Isinglass is made from the ‘‘sounds” or air bladders 
of certain fishes like the cod, hake, and squeteague. These industries 
were illustrated by 24 samples of fertilizers and 25 samples of glue and 
isinglass. Nearly 60 different samples of oils, valuable for medicinal 
or mechanical purposes and obtained from fishes, were shown. The 
best-known and most extensively used are cod-liver, whale, sperm, and 
menhaden oils, but many others are particularly adapted for special 
uses, for which they are superior to other animal and mineral oils. 
Sponges, although taken in the waters of only one State (Florida), 
are objects of an important fishery. The economic species were rep- 
resented by a series of dried specimens of different grades and sizes. 
Ivory, bone, and shell are among the products of the fisheries used 
to a certain extent in the arts and industries, and there were shown 
examples of walrus and narwhal tusks, sperm-whale teeth, baleen or 
whalebone, both crude and prepared for use, and the well-known tor- 
toise shell, in the form of shells, rough and polished, of the hawksbill 
tortoise-shell turtle. 
The shells of mollusks are employed for various purposes. A com- 
paratively new use to which the shells of our fresh-water mussels have 
been put is in the manufacture of pearl buttons. This business, while 
only established a few years ago, has attained large proportions in the 
Mississippi basin. <A full series of the shells utilized in button-making 
was shown, together with buttons in various stages of manufacture. 
The mollusks yielding shells suitable for buttons also produce very 
beautiful and valuable pearls, examples of which were exhibited. 
The skins of water animals and some fishes are now largely utilized 
in the manufacture of leather goods of all kinds, and their use could 
