116 Zoologica: N. Y. Zoological Society [III; 3 



comparable with those which sometimes impel a person who has 

 been sitting for hours in a dimly-lighted room, to stand at the 

 window or open door or to step out into the sunlight. 



Thus while it is easy to interpret many of the activities of 

 the social Silvanids as adaptive reflexes it is difficult to assign to 

 such stimuli as light, contact, chemicals, etc., the leading role 

 which they have in the theories of Loeb and Bohn. Much of the 

 behavior of the beetles, such as their treatment of the coccids, the 

 building of the cocoon, mating, the guarding of the entrance, 

 etc., so obviously depends on internal or physiological states that, 

 in so far it has not become completely mechanized, we may more 

 properly regard it as made up of cyclical activities like those 

 recognized by Herrick (1910), Craig (1918) and others in birds. 

 Craig especially has shown how much of the behavior of birds 

 can be interpreted as cycles of appetence, or appetite and aver- 

 sion, which he defines as follows: "An appetite (or appetence, 

 if this term may be used with purely behavioristic meaning), 

 so far as externally observable, is a state of agitation which 

 continues so long as a certain stimulus, which may be called the 

 appeted stimulus, is absent. When the appeted stimulus is at 

 length received it stimulates a consummatory reaction, after 

 which the appetitive behavior ceases and is succeeded by a state 

 of relative rest. An aversion is a state of agitation which con- 

 tinues so long as a certain stimulus, referred to as the disturbing 

 stimulus, is present; but which ceases, being replaced by a state 

 of relative rest, when that stimulus has ceased to act on the 

 sense-organs." 



Rignano (1920) gives this same conception a more general 

 physiological formulation in the following passage: "Every 

 organism is a physiological system in a stationary condition and 

 tends to preserve this condition or to restore it as soon as it is 

 disturbed by any variation occurring within or without the 

 organism. This property constitutes the foundation and essence 

 of all "needs," of all "desires," of all the most important organic 

 "appetites." All movements of approach or withdrawal, of 

 attack or flight, of taking or rejecting which animals make 

 are only so many direct or indirect consequences of this perfectly 

 general tendency of every stationary physiological condition to 

 remain constant. We shall soon see that this tendency in its 



