OPERATIONS AT THE LABORATORY. 
521 
no place where the development and life histories of species, such as the 
lobster, cod, bluefish, mackerel, and sea bass, can be more advantage- 
ously studied than in the hatching rooms connected with the laboratory 
of this station. 
The Commissioner, Professor McDonald, has been engaged, during 
a considerable part of the time which he has been able to spare from 
his official duties, in devising improvements in the methods of display- 
ing living objects in the aquaria under the best conditions. This has 
been accomplished by allowing the light to pass down through the water 
from above and cutting off the view from the upper surface entirely. 
This, with tastefully arranged rock work, algae, polyps, and a limited 
number of fishes, gives picturesque effects of marvelous beauty, and 
also renders the organisms confined in the aquaria capable of being 
studied under conditions natural to them. Sea-anemones, with their 
flower-like disks of tentacles fixed to the rocks, active stickle-backs, the 
gorgeously colored sea bass, scup, crevalle, and mackerel swimming 
back and forth through the grottoes in these aquaria, make a combina- 
tion of most beautiful objects, which have been sources of perennial inter- 
est and instruction to the many hundreds of visitors who have passed 
through the hatching rooms of the station during the past summer. 
These displays have also afforded the naturalists very valuable oppor- 
tunities for studying some of the comical habits of the common deni- 
zens of the waters in the vicinity of the station. Some very important 
and significant habits have thus been made out as characteristic of 
given types. The tautog, for example, has the habit of lying over on its 
side, first digging out a bed for itself in the sand or gravel; here it 
rests as contented as a pig in a puddle till some unwary victim comes 
along to tempt the fish from his lair. Some such habit as this may have 
given rise to the flounders, which have unquestionably descended from 
fishes with an eye symmetrically placed on either side of the head. 
The Commissioner has also been experimenting, with most promising 
results, with new methods of aeration, so as to maintain life in the aqua- 
ria without a change of seawater. The presence of* the water supply 
in the tanks is utilized in such a way as to form an aerating apparatus 
which carries a stream of air divided into fine bubbles through some of 
the aquaria, from which the supply of water is entirely cut oft’. The 
water used in effecting aeration in this manner can be used to operate 
other overflow aquaria, or such as are fed by constantly renewed supplies 
of sea water. A plan such as this will make it possible to have marine 
aquaria operated at the Central Station at Washington, the aeration 
of the salt water being easily effected by the utilization of the supplies 
of fresh water used in the operation of fresh -water aquaria. This will 
make that station doubly valuable in conducting experimental work, 
and give increased interest to the display of fresh water fishes, to which 
it will then be possible to add many marine forms for exhibition in the 
