REACTIONS OF FISHES TO ATMOSPHERIC GASES 263 



8. The two species tried reacted negatively to a gradient of 

 acetic acid in boiled water but some of the species did not react 

 to ammonia in concentrations which produce death (p. 252). 



9.- Some fish establish 'preferences' or apparent preferences for 

 one end of the experimental tanks for reasons obviously due to 

 the experimental conditions (pp. 246, 261). 



10. There is a large similarity of reaction among fishes that 

 differ widely taxonomically, which indicates the possibility of 

 groupings which are of generic, ordinal, or family value, but 

 which bear no relation to existing taxonomy (p. 259). 

 • 11. The carbon dioxide content of the water is probably the 

 best single index of the suitability of the water for supporting 

 fishes (p. 261). 



The writers are indebted to Dr. H. N. McCoy and Mr. C. H. 

 Viol, of the Department of Chemistry, for advice in connection 

 with the control of gases, and to Dr. W. Crocker for the loan of 

 apparatus used in some of the work. Also to Dr. S. E. Meek, 

 of the Field Museum, for the identification of the fishes, and to 

 Mariner and Hoskins for chemical analyses without charge. 



July 29, 1912. 



BIBLIOGRAPHY " 



Abbott, C. C. 1870 Notes on fresh water fishes of New Jersey. Am. Nat., 

 vol. 4, pp. 99-117. 



1875 Notes on some fishes of the Delaware River. B. Notes on the 

 winter habits. Report U. S. Fish Commission; 1875-76, pp. 841-845. 



Allee, VV. C. 1912. An experimental analysis of the relation between physio- 

 logical states and rheotaxis in Isopoda. Jour. Exp. Zool., vol. 13, pp. 

 2G9-344. 



American Health Association 1905 Report of the committee on standard 

 methods of water analysis. Jour. Inf. Dis., May, Supl., pp. 1-141. 



Birge, E. a. 1904 The thermocline and its biological significance. Trans* 

 Am. Micro. Soc, vol. 25, September, pp. 5-33. 



1907 a Oxygen dissolved in the waters of Wisconsin lakes. Report 

 Wis. Com. of Fisheries, pp. 118-139. 



1907 b The respiration of an inland lake. Trans. Am. Fisheries, 

 Soc, pp. 223-241. 



