248 THE BEHAVIOR OF LOWER ORGANISMS. 



In ourselves the stimuli which induce the negative reaction bring 

 about the subjective state known as pain (in varying degrees, from dis- 

 comfort or dislike to anguish), and popularly we consider that the draw- 

 ing back is due to the pain. Is there ground for this view? Or is the 

 reaction entirely accounted for by the chemical and physical processes 

 involved? When the burnt child draws its hand back from the flame, 

 does the state of consciousness called pain have anything to do with 

 the reaction ? 



Without attempting to answer this question, we wish to point out 

 the bearing of possible answers on our problem in the lower organisms. 

 If we hold that in man we cannot account for the reaction without tak- 

 ing into consideration the pain, then we must hold to the same view 

 for the lower organisms. If we maintain that in man we cannot 

 account for the selection of such a heterogeneous group of conditions for 

 the negative response conditions seeming to have nothing in common 

 save that they cause pain without taking into consideration the pain, 

 then we are forced to the same conclusion in the unicellullar organisms, 

 for here we have a precisely parallel series of phenomena. Anyone, 

 then, who holds that pain is a necessary link in the chain of events in 

 man must consider that we are undertaking a hopeless task in trying to 

 account for the reactions of the lower organisms purely from the chem- 

 ical and physical conditions. And the converse is also true. Anyone 

 who holds that we can account fully for the reactions of Euglena or 

 Paramecium, purely from the physico-chemical conditions, without 

 taking into account any states of consciousness, must logically hold that 

 we can do the same in man. The method of trial and error implies 

 some way of distinguishing error ; the problem is : How is this done? 

 The problem is one, so far as objective evidence goes, throughout the 

 animal series. 



We can, of course, know nothing of pain in any organism except 

 the self, and we can, in a purely formal way at least, solve our problem 

 equally well (or equally ill) without taking pain directly into consider- 

 ation. Even in man we must hold that pain is preceded or accom- 

 panied in every case by a certain physiological condition. And if there 

 is something common to all states of pain, it would appear that there 

 must be something common to all the physiological states accompany- 

 ing or preceding pain. We thus get a common basis for all the nega- 

 tive reactions ; if they are preceded or accompanied by a common 

 physiological state, this state will serve formally as an explanation for 

 the common reaction, fully as well as would a common state of con- 

 sciousness. The facts could be formulated as follows : In any animal, 

 from the lowest up to man, a certain heterogeneous set of agents, which 

 are in general injurious, produce a certain physiological state, common 



