28o BEHAVIOR OF THE LOWER ORGANISMS 



behavior of a floating Amoeba in attaining a solid support, as described 

 on page 8, or to the food reaction illustrated in Fig. 21. Further, as 

 we have seen on page 20, Amoeba may at different times react in oppo- 

 site ways to the same stimulus. 



Indeed, consideration shows that it is impossible to apply rigidly the 

 conception of a reflex, as an invariable reaction to a definite stimulus, 

 to the behavior of any organism having more than one motor reaction 

 at its command. James ("Psychology," Vdl. I, p. 21) and Pearl (1903, 

 p. 704) have given us sketches of what would be the behavior of an 

 organism whose acts were purely reflex. Taking the reaction to food 

 as an example, James says : "The animal will be condemned fatally and 

 irresistibly to snap at it whenever presented, no matter what the cir- 

 cumstances may be ; he can no more disobey this prompting than water 

 can refuse to boil when a fire is kindled under the pot. His hfe will 

 again and, again pay the forfeit of his gluttony. Exposure to retaliation, 

 to other enemies, to traps, to poisons, to the dangers of repletion, must 

 be regular parts of his existence. His lack of all thought by which to 

 weigh the danger against the attractiveness of the bait, and of all voli- 

 tion to remain hungry a little while longer, is the direct measure of his 

 lowness in the mental scale" (I.e., p. 21). Such a picture has only to 

 be presented to make us see the impossibility of constructing the entire 

 behavior of an organism out of such irresistible reflexes. For the re- 

 actions to dangers and er^emies must then be reflexes, as well as the 

 reactions to food, and the two are incompatible. Suppose the food and 

 the danger are present together, as often happens. The organism can- 

 not react fatally and irresistibly to both, for the movements required are 

 in opposite directions. It must decide to react either with relation to 

 one or to neither, and in either case the fatality arxd irresistibihty of at 

 least one of the reflexes disappears. 



If, then, we consider the reflex an invariable reaction to a given stimu- 

 lus, we cannot hold that behavior in lower organisms is made up of 

 reflexes. Indeed, the fact that stands out most clearly in the behavior 

 is the following: Each stimulus causes as a rule not merely a single 

 definite action that may be called a reflex, but a series of "trial" move- 

 ments, of the most diverse character, and including at times practically 

 all the movements of which the animal is capable. The reaction to a 

 given stimulus depends on the physiological state of the organism, not 

 alone on its anatomical structure; and physiological states are variable. 

 This is true both for the infusoria and for man. 



The attempt to characterize the behavior of the lower organisms as 

 purely reflex has risen from the desire to show that the structural con- 

 ditions of the organism and the physical and chemical action of the 



