Vol. XXV. November, 1913. No. 6 



BIOLOGICAL BULLETIN 



THE RESISTANCE OF FISHES TO DIFFERENT CON- 

 CENTRATIONS AND COMBINATIONS OF 

 OXYGEN AND CARBON DIOXIDE. 



MORRIS M. WELLS. 



PAGE 



I. Introduction 



II. Plan of Experimentation . 324 



III. Apparatus 



IV. Reactions of the Fishes - 329 



V. Resistance of the Fishes -332 



VI. General Discussion 33 



1. The Breeding Behavior of the Adults 33$ 



2. Resistance of the Eggs and Fry . 34O 



3. Resistance and Reactions of Young Fishes 34* 



4. Resistance and General Behavior of Adults 34* 



VII. Summary 345 



Acknowledgments and Bibliography. 



I. INTRODUCTION. 



In a recent article (Shelford and Allee, '13) entitled 'The 

 Reactions of Fishes to Gradients of Dissolved Atmospheric 

 Gases" the authors discussed the physiological effects of gases 

 in solution, on fishes, and presented a table showing the results 

 of some preliminary experiments upon the resistance of fishes to 

 low oxygen. They also report some experiments on the resistance 

 to high concentrations of carbon dioxide. 



It is the purpose of this paper to report some further experi- 

 ments, which have been carried on in the same laboratory, with 

 the purpose of determining what position, varying concentrations 

 of oxygen and carbon dioxide, hold, in the physiology and thus 

 the ecology and economy of fishes. The experiments herein 

 reported were undertaken at the suggestion of Dr. V. E. Shelford, 

 and have been carried on in his laboratory, with the use of part 

 of the same apparatus (gas control) that was used in the experi- 

 ments referred to above. 



