26 
new projects and new pollutions. There has been too much bald scientific 
and business sophistry in the matter. Ichthyologists, biologists, engi- 
neers, Sanitarians, industrial chemists, and business men, without con- 
sultation, cooperation, or critical analysis, have proceeded on the basis 
of their imperfect and fragmentary knowledge to draw inferences as to 
the effect of this or that on fishes. The inferences of some scientists are 
not especially more in keeping with an equitable decision relative to a 
policy favorable to the public interest than was the exclamation of a 
manufacturer when confronted with a law intended to stop his factory 
from polluting streams: “What! stop a great industry because of a few 
fish!” The pollutions of manufacturing plants and city sewage have 
greatly aggravated the depletion, or in some instances have completed 
the destruction, previously started by heedless fishermen; but the pollu- 
tions are far more serious than the initial injury because they preclude 
the possibility of easy recovery. We have all sinned alike until it 
becomes imperative that we take stock of our knowledge, now that we 
are under the pressure of numerous problems demanding immediate solu- 
tion because of the great war. Some means of approximately measuring 
the harm which pollutions do, is needed at once. Our knowledge of the 
subject is incomplete and unorganized. A number of crucial questions 
have frequently called for answers in the past few months, and it is the 
purpose of this paper to state these problems, to emphasize the need for 
further definite investigation for their solution, and to give a general 
indication of the trend of existing data bearing on them.: The general 
subject of the relation of aquatic animals to the physical and chemical 
conditions of their environment has only recently begun to receiye syste- 
matic attention. (Birge and Juday,’11; Forbes and Richardson, ’13; 
Shelford, ’17, 18.) The tables here included are provisional and incom- 
plete, but they indicate what kind of tables would be found highly useful 
were the data for them in hand, and they also indicate the pressing need 
for further investigation. 
The writer wishes to express here his indebtedness to Mr. E. B. 
Powers and Mr. W. D. Hatfield for assistance in preparing this paper. 
NINE CRUCIAL QUESTIONS IN CONNECTION WITH PROBLEMS OF 
POLLUTION IN RELATION TO UsEFuL AguatTic ANIMALS 
On the basis of the author’s personal studies, an examination of the 
literature of the subject, and discussion with persons engaged in several 
related lines of investigation, an attempt is here made to point out means 
of answering nine crucial questions, relating to the survival, well-being, 
abundance, and quality of useful aquatic animals, which are intimately 
associated with the question of the economical use of wastes and the satis- 
factory disposal of such effluents as can not be worked up. But the final 
practical solution of so complex a problem calls for something more than 
a knowledge of the toxicity of wastes and the best methods for deter- 
mining it, and insistence on the preservation .of food and breeding 
