96 ANIMAL AGGREGATIONS 



these are anesthetized, the Winded fish respond very httle, if at all, 

 to the passing of others. 



Various insects and other animals give no responses to aerial 

 vibrations easily detected by the human ear, but readily respond to 

 the same sounds when their receptacle is placed upon the piano pro- 

 ducing the vibrations. Emerson (1929) has demonstrated that in 

 the social termites mechanisms exist for producing substratal vibra- 

 tions which can be detected at times by the unaided human ear, and 

 easily when a microphone is used. He suggests that this may be one 

 means of communication between these insects. Rabbits have long 

 been known to signal by ground thumpings. The extent to which 

 this kind of vibration is used in the aggregations with which we are 

 specifically concerned awaits investigation. 



Buxton (1923) records an instance of co-ordinated movement 

 among arctiid moth larvae which illustrates some of the possibilities 

 of this type of integration. These caterpillars live in webs on herb- 

 age in groups numbering several scores. If the web is disturbed, 

 the larvae jerk the anterior ends of their bodies sidewise with a sharp 

 flicking movement. All jerk together and maintain the reaction at a 

 rate of about twice a second for as much as 20 to 30 seconds. Then 

 they cease this movement and resume feeding. If they wander even 

 an inch or so from the web, they do not take part in this movement. 

 If an elongated web is chosen for the experiment (for example, a web 

 4X12 inches), the movement of the larvae is not simultaneous, but 

 waves of movement may be seen to pass through the mass of larvae 

 from the point of disturbance so that the movement is organized 

 but not synchronous. Obviously, the stimulus is conducted along 

 the web. More mature larvae that have left the web do not generally 

 give this movement when disturbed, although they may so respond 

 when another crawls over them. 



POSSIBILITY OF BIOPHYSICAL INTEGRATION 



It is probably too early as yet to speculate with profit concerning 

 the possibility of other, more subtle methods of group integration, 

 such as the observations of Gurwitsch (1926), Borodin (1930), 

 and others suggest may result from exploration of the field of bio- 



