PROGRESS IN BIOLOGICAL INQUIRIES, 1921. 5 
knowledge as we have of the life history of the crab—in short, upon 
the results of scientific work previously done. Emphasis must be 
put upon the adverb of time. The significant thing is that the work 
must in great part, at least, have been already done; for knowledge 
can not be secured immediately; one can not produce the life history 
of an aquatic animal upon demand; it is the result of painstaking 
study through a period of time which can not be fixed in advance, 
and by the application of methods which can not be definitely plotted 
beforehand. 
It is work of this kind which must be done, and continuously done, 
so that gradually and steadily we learn more and more about our 
fishery animals, if we are to be ready at all times to meet the chang- 
ing problems of regulation and exploitation as they arise. 
The scientific knowledge which is the basis of the future welfare 
of the fisheries requires not only time and application, but also 
skill and special training. Of greatest importance are the services 
of men who have not only natural qualifications and the preliminary 
training which institutions of learning can give, but also such special 
experience, interest, and devotion as can be gained only as the result 
of prolonged application to fisheries studies. Something may be done 
with inexperienced and changing agents, but the most successful 
and economical work will be done with a trained and continuing 
force. 
In the following report will be found not an account of what might 
have been done, or what ought to have been done—but rather a state- 
ment of the progress which has been attained under the difficult con- 
ditions by which the scientific work of the Bureau has been circum- 
scribed. It may be added that the Bureau again closes the year with 
a less effective force than it had at the beginning. Two members of 
the already depleted staff have resigned to accept better paying posi- 
tions elsewhere, and two (including one rendering largely volunteer 
service) have died and not been replaced. Special acknowledgments 
are due to those whose interest and loyalty have held them in the 
public service. 
In reviewing the subject of investigation it must be understood 
that while the Bureau has a definite policy of restricting expendi- 
tures to investigations of the most direct practical bearing, it is not 
entirely untrammeled in the selection of subjects of investigation. - 
The qualifications of the personnel available necessarily determine in 
part the character of problems which can be profitably attacked. 
STUDIES OF FISHES. 
THE PACIFIC SALMON. 
When consideration is given to the magnitude of the industries 
based upon the salmons and their near relatives, to the unrivaled 
rank which some of these fishes hold in the realms of sport and 
recreation, to the comparative ease with which the more important 
species may be brought to virtual extermination, and to the fact 
that all important species are the subject of artificial propagation, 
it is apparent that no group of fishes demands a greater share of 
attention in the way of scientific study. 
