BEHAVIOR AGREEMENT AMONG ANIMALS. 



313 



importance. There is agreement in reaction to factors of prime 

 importance and disagreement in respect to factors differing 

 strikingly in the different situations in which the animals are 

 living within the community. 



The diagram for the pool species is introduced to show how 

 strikingly it differs from that of the rapids community. Though 

 agreement is not indicated here, our experience with the reactions 

 of pool fishes and invertebrates to chemical differences in w-ater, 



POSITIVE REACTIONS 



HYDROPSYCHE OR RAPIDS COMMUNITY 



SPECIES 

 ETHEUSTOMA 



CAMBARUS 



GONIOBASIS 



HYDRUPSYCHE 



ARGIA 



PERLA 



HEPTAGENINAE 



PSEPHENLS 



STRATA 



UNDER STONES 



^STRONG CURRENT 

 POSITIVE 

 REACTIONS T0< HARD BOTTOM 



^MEDIUM LIGHT 



AMONG STONES 

 WEAK LIGHT 

 KINAESTHESIA 



1 UNDER STONES 

 | ON STONES 

 J STRONG LIGHT 



Fu;. 40. Showing the agreement and disagreement of reaction of the rapids 

 c;mmunity. Note agreement of reaction to bottom and current and disagreement 

 of two other reactions, related to the level at which the animals live. Each re- 

 action is represented on a scale of 100 and if no other factors entered in the total 

 should be 400 and the space all occupied. For strong agreement in positive re- 

 actions to stones see Fig. 33, p. 307. 



suggests that such differences may be of much importance to all 

 the species. 



The difference emphasized by the presence of two types of 

 reactions not shown in the other charts, namely, a strong prefer- 

 ence for bottom involving sand (see Fig. 32 for details in case 

 of the fishes) and burrowing which are reactions not shown by the 

 rapids species at all. The non-burrowing specie's are positive 

 to current, the burrowing species do not respond within ordinary 

 lengths of time. The reactions to light show much more sharp 

 negativeness than in the case of darters and crayfish. The 

 community is clearly unsolved as far as agreement is concerned 



