222 C. F. PHIPPS. 



decreasing the ability of the tissues to take up oxygen. Chlore- 

 tone is a soporific and has a depressing or inhibiting effect upon 

 certain metabolic processes. Starvation decreases metabolism 

 by removing the material to be oxidized. Such reagents and 

 treatments are known to have specific effects on metabolism 

 and they also cause reversals in phototaxis, therefore the re- 

 sponses are related to the metabolic rate of the animal. 



Jennings ('04) says that physiological states are the most 

 important determining factors in reaction and behavior. By 

 physiological states he means the varying physiological condi- 

 tions as distinguished from permanent anatomical conditions. 

 Can we be sure that such physiological states do exist? If we 

 subject animals to the same external conditions and give the 

 same stimulus, and the animals react differently, then the 

 difference must be due to variations in internal conditions; else 

 the reactions would always be the same. A stimulus changes 

 the physiological state of the animal as a whole, and this change 

 in physiological state induces a certain type of reaction. 



My thanks are due to Dr. V. E. Shelf ord under whom this 

 work was done, and to Dr. W. C. Allee and Mr. M. M. Wells 

 for valuable suggestions. 



BIBLIOGRAPHY. 

 Allee, W. C. 



'12 An experimental Analysis of the Relation between Physiological States and 

 Rheotaxis in Isopoda. Jour. Expt. Zool., Vol. 13, No. 2. 

 Banta, A. M. 



'13 Experiments on the light and tactile reactions of a cave variety and an 

 open water variety of an amphipod species. Proc. Soc. Exp. Biol, and 

 Med., Vol. 10, May 21, 1913. 

 Cushny, A. R. 



'10 Pharmacology and Therapeutics. loth ed. 744 pp. Phil. 

 Holmes, S. J. 



*oi Phototaxis in Amphipods. Am. Jour. Physiol., Vol. 5. 

 '03 Sex Recognition among Amphipods. Biol. Bull., Vol. 5. 

 'os The Selection of Random Movements as a Factor in Phototaxis. Jour. 

 Comp. Neur., Vol. 15, pp. 98-112. 

 Jackson, H. H. 



'10 Control of Light Reactions in Hyalella. Jour. Comp. Neur. and Psy., 

 Vol. 20. 

 Jennings, H. S. 



'04 Physiological States as Determining Factors in the Behavior of Lower 



Organisms. Carnegie Inst, of Wash. Publ. 16, p. 109. 

 '06 Behavior of Lower Organisms. Columbia Univ. Press. 



