46 REPORT OF THE COMMISSIONER OF FISHERIES. 
Other subjects of investigation were the parasites of fishes and the 
effect of such parasites upon the vitality of the individuals; the 
effect upon fishes of certain mineral salts which may be present either 
as a normal constituent of some spring waters or as a consequence of 
pollution; the metabolism of fishes and oxygen utilization, subjects 
which have a bearing upon the propagation and rearing of fishes; 
the bacteriology of fishes; the biology and the utilization of sea 
mussels; and the possibilities of utilization of other waste fishes. 
As usual the facilities of the laboratory were extended to a few inde- 
pendent investigators whose studies were pursued without expense 
to the Bureau. 
The Beaufort, N. C., laboratory is a center for investigations that 
look to the better development of the fisheries of the South Atlantic 
coast. Allusion has been made to the study of the mullet and to 
the survey of fishing grounds which has revealed opportunities for 
offshore winter operation and contributed to the development of 
a fishery that is as yet unduly limited. The successful experiments 
in terrapin culture are also more fully described elsewhere. Special 
attention is being devoted to the breeding habits of fishes, the larval 
development of fishes, and, as opportunity offers, to the possibilities 
of propagation of certain sea fishes which support important fisheries 
in the South Atlantic States. Interesting observations were made 
and a report was prepared dealing with the habits of certam species 
of small fish that are denizens of brackish and fresh waters and 
that: are serviceable in the extermination of mosquito larve and 
hence in the maintenance of public health. 
Efficient study of the food of fishes and of the movements of 
fishes, as directed by the search for food, or the avoidance of enemies, 
demands an exact knowledge of the forms of animal and plant life 
which may be encountered in the local waters or which may be found 
in the stomachs of the fishes. Cazeful systematic studies of certain 
groups of animal and plant life have therefore been in progress for 
some time. yee the past fiscal year there was completed for 
publication a valuable report on the sharks and rays of the Beaufort 
region; and another comprehensive report dealing with the decapod 
crustacea, a group that includes the crabs and other forms of most 
direct economic usefulness, has also been completed and submitted 
for publication. Systematic studies of certain groups of fish para- 
sites have been completed. A report of the alge of the region is 
nearing completion, while the diatoms and protozoa, among the 
lowest forms of minute plant and animal life, as well as the higher 
fishes, are now subjects of investigation. 
In the assurance that the development of commercial fisheries will 
soon demand more strongly the conservation of important shellfish, 
serious attention is being given to the life history of the quahaug or 
hard clam and the principal crustacean forms. 
The Beaufort laboratory has also been found a favorable place 
for the prosecution of certain special problems that have not a. 
particular regional significance. At this place there are pursued 
investigations of the toxicity of certain chemicals to marine borers 
and of the protection of wood against these disastrous pests, in which 
studies the Bureau has enjoyed the cooperation of the forest products 
laboratory of the Forest Service and the sympathetic interest of 
railway companies and other commercial bodies. 
