FISHES AND THEIR SURROUNDING MEDIUM. 299 



to the gills or whether the general integument of the body were 

 likewise concerned. 



Altogether the results of about 1 50 experiments have been 

 taken into consideration in arriving at the conclusions here pre- 

 sented. These experiments were carried on during the summers 

 of 1904 and 1905 at the biological laboratory of the Bureau of 

 Fisheries at Woods Hole, Mass., and during the spring of 1905 

 at the New York Aquarium. Acknowledgments are due to 

 the officials of the Bureau of Fisheries for facilitating the prog- 

 ress of this work ; and to the director of the New York Aqua- 

 rium, Mr. Chas. H. Townsend, who placed at my disposal a 

 room equipped for research, and provided me with abundant 

 material throughout. My thanks are likewise due to Prof. W. C. 

 Sabine, of the department of physics of Harvard University, for 

 valuable criticism, and to Mr. D. W. Davis, assistant at the Fish- 

 eries Laboratory, for help during the earlier portion of the work. 



Full details of these experiments, including the methods em- 

 ployed, and the precautions taken, must be deferred to the more 

 extended paper which will soon appear. In the meantime, the 

 principal results may be summarized as follows : 



i . Certain brackish and salt-water fishes were unable to survive 

 even a gradual transfer to pure fresh zvater, though enduring an 

 abrupt transfer to water of a very lotv degree of salinity. Tints 

 fresh vvater, as suc/i, proved fatal to these fis/ies, the degree of ab- 

 ruptness of t/ie change being of secondary importance. 



These conclusions are drawn from experiments upon the three 

 local species of killifishes (Fundulus lieteroclitus, majalis and dia- 

 pJianus}, together with the allied species, Cyprinodon variegatus ; 

 likewise the white perch (Morons americana), cunner (Tantogo- 

 labnts adspersns), tautog (Tantoga onitis), sculpin (Myoxocephalus 

 octodecimspinosus}, and winter flounder (Pseudopleuronectes ameri- 

 camis^. The death of a varying (often a large) proportion of 

 specimens of F. diaphamts, when transferred from mildly brackish 

 (sp. gr. 1.0021.006) to pure fresh water was certainly unex- 

 pected, since this species in nature is not confined to brackish 

 waters, but is indigenous to lakes and streams far from the coast. 

 F. heteroclitus, likewise, is known to occur at times in fresh water ; 

 but the writer has found (contra Garrey J ) that in nearly every 



1 BIOLOGICAL BULLETIN, Mar., 1905. 



