298 BEHAVIOR OF THE LOWER ORGANISMS 



ferent physiological state A, which of itself produces no reaction. But 

 this is invariably followed by the shading of the chlorophyll bodies, 

 interfering with metaboHsm and inducing the physiological state B, re- 

 sulting in a negative reaction. Thus the state A is regularly resolved 

 into the state B. In accordance with the law of the resolution of physio- 

 logical states, this resolution in the course of time becomes spontaneous. 

 A passes at once to B and a negative reaction occurs, even when the 

 colorless anterior tip alone is shaded. In unicellular organisms a condi- 

 tion so reached would naturally continue to succeeding generations, since 

 the organisms in reproducing merely divide. 



In the same way the defensive reaction of the sea urchin when 

 shaded could be produced. The condition A, induced by the shade, is 

 usually resolved into the condition B, induced by the attack of an enemy, 

 and resulting in the defensive movement. This resolution in the course 

 of time may then become spontaneous, so that the sea urchin now reacts 

 defensively even when a cloud passes over the sun. This condition 

 could be continued to succeeding generations only if acquired charac- 

 ters are inherited. 



Thus through the operation of the. law of the resolution of physio- 

 logical states the following general result will be produced: If a given 

 agent induces a physiological state A, and this is usually followed by a 

 second state B, then in time the given agent will produce at once the 

 response due primarily to B. The organism will have come to react 

 to A as representative of B. 



We do not know whether the development of reactions to representa- 

 tive stimuli has actually taken place in this way, or not. But the fact 

 that there is a factor, whose existence is demonstrated, that would pro- 

 duce exactly these results, certainly suggests strongly the probability 

 that they have been at least partly brought about in the way above set 

 forth. If the law of the resolution of physiological states is actually 

 operative throughout behavior, the effect would be to make behavior 

 depend on the results of the animal's own action. This would produce 

 behavior that is regulatory, such as we actually find to exist. 



(S) The reaction to a given external stimulus depends, as we have 

 previously seen, on the physiological condition of the organism, not 

 alone on the nature of the external change. The physiological condi- 

 tion depends partly on whether the normal stream of life activities is 

 proceeding uninterruptedly. In certain physiological states, such as 

 hunger, the processes are not proceeding normally. This impels the 

 organism to a change, so that to almost any external stimulus it may 

 react in a way that tends to bring about a change. The hungry sea 

 anemone in this condition reacts positively to all sorts of neutral bodies ; 



