OBSERVATIONS ON THE AQUARIA AT CENTRAL STATION. 
5 
The plant ancl animal life lias been supplied by seining expeditions to Chesapeake 
Bay, and by several lots of specimens brought by tlie Commission’s steamer Fish Hawk 
on her returns from work of investigation. 
During the springs of 1889 and 1890 a number of the eggs of the horse-shoe crab 
■(: Limulus ) were received by mail from Delaware Bay by Dr. Hugh M. Smith, of the Fish- 
eries Division of the Commission. They were sent by Mr. E. S. Howell, of Dias Creek, 
NTew Jersey, packed in wet sand in small tin boxes. They hatched and developed until 
about three-eighths or one-half inch long, when they began to die off gradually, probably 
from lack of proper food. The adults in the aquarium feed on beef, clam, and fish. 
A number of nests of the 2-spined stickleback ( Gasterosteus aculeatus) were built, 
affording an opportunity for observation of the breeding habits of that species. The 
nest is composed of a mass of vegetable fiber and shreds of algtc, living and dead, 
deposited on the bottom of the aquarium or on the flat upper surface of a piece of 
rock. It is not so ^elaborate as that of the 4-spined species, but is bound together in 
the same manner by means of a thread spun by special secretive glands, as described 
by Prof. John A. Byder, in the Bulletin of the Commission for 1881, in the case of the 
4-spined species. The young are protected by the male after hatching by driving away 
other fish, and by giving them an education in self-protection. He will dart at the 
young as if about to devour them, causing them to take refuge among the plants and 
stones, to again emerge as he darts off in pursuit of fish venturing near. With a 
vigilance that is incessant and untiring they are thus guarded and driven under cover 
until finally they flee and hide at the passing of a shadow over the water. 
During the spring and summer of 1889 four species of Cyprinodonts spawned in 
the aquaria and their spawning habits and sexual coloration were noted. 
The readiness with which these small species spawn in captivity justifies the belief 
that when adequate conditions are afforded for our larger fishes similar results will 
be attained with them. Such a consummation would undoubtedly lead to the most 
practical advance possible in our knowledge of the habits of our fishes. 
It was noticed, on transferring some white perch (Boccus americanus) suddenly 
from fresh to salt water, that they were so buoyant as to be unable to swim beneath 
the surface, the dorsal fin and part of the back being out of the water, and that it was 
only after some days that they acquired the proper specific gravity and could swim 
about normally. This probably explains the necessity for a gradual change from water 
of one density to another, they not appearing to suffer from the effects of the salinity. 
In a similar experiment with some eels they were able to keep near the bottom, 
but had a tendency to stand on their heads. 
A very interesting experiment has been made in confining fishes infected with 
fungus (generally as a result of injuries received in transportation) and such as are 
infested with parasites, in brackish water for a time. It is well known by all who 
handle live fish that they are very easily injured. The scales may be detached, the 
fins torn and abraded, the lips bruised and torn from knocking against the sides of 
the can or box, and the whole mucous coating and skin more or less scratched and 
bruised. Many of these injuries do not show for some days, and it is possible that 
where fish are speedily restored to natural conditions at the end of their journey they 
may find in the mud or in some other source a healing specific which will effect a cure. 
In the aquarium, however, they are soon attacked by fungus (Saprolegnia), and in their 
generally depressed condition, refusing food although undoubtedly slowly starving, 
