48 ANIMAL AGGREGATIONS 



different end-responses in the expression of one and the same bio- 

 logical principle, involving therefore only the vague type of utility 

 necessary for the cumbersome working of natural selection and with 

 no more suggestion of purpose than is inherent in scientific concep- 

 tions generally. 



This analysis of prototaxis shows that it is in the main a renaming 

 of the type of activities usually called "instinctive," with the exten- 

 sion of this sort of action to include the behavior of tissue cells and 

 with a deprecation of the tendency to include a distinct teleological 

 element which is usually present in discussions of instincts. The 

 question immediately arises as to what social instincts or appetites 

 may mean, and .whether or not they are capable of analysis. 



Szymanski (1913) undertook to investigate this problem by com- 

 paring the reactions of isolated caterpillars of Hyponomeuta and of 

 Arye with those given by groups when placed under the same general 

 conditions. Recognizing the fact that social reactions are not readily 

 analyzed, Szymanski undertook to separate them into two cate- 

 gories: (i) those peculiar to the individual, which, if fortunate, make 

 possible the living-together of individuals as a social group, and 

 which may be called "primary reactions"; and (2) responses which 

 arise as the result of the living-together of many individuals, and 

 which may be called "secondary reactions." 



In order to distinguish primary and secondary responses in a social 

 group, Szymanski suggested and used the following procedure. The 

 reactions of the individual are first studied with a view to finding the 

 usual responses given to various stimuli; thereafter one studies the 

 behavior of individuals as members of a group. In the latter study it 

 is frequently possible to recognize elements of behavior which have 

 been observed in the isolated individuals. If all the reactions given 

 by the individuals of a colony can be recognized as primary re- 

 sponses, such as would be given were all the animals isolated, the 

 problem of group behavior is solved without the need for recognition 

 of secondary or essentially social behavior; but if there is a residue of 

 behavior which cannot be recognized as primary, then this is to be 

 regarded as the secondary or true social behavior. 



Szymanski so analyzed the responses given by caterpillars of 



