BEHAVIOR OF VERTEBRATES 453 



variations in the evaporating power of air. In this case the 

 conditions were such as would tend to dilute or concentrate 

 the plasma either in the peripheral sense organs or in the animal 

 as a whole. Though associations are formed, Shelford says, 

 they go hand in hand with and can hardly be distinguished 

 from other type modifications * * * There is no reason to 

 assume that associative memory is essentially different from 

 the type of modification here described. * * * It seems probable 

 that many of the simple problems of associative memory must 

 be referred to the bio-chemist for solution." 



Fish. — Shelford (29) also has published an elaborate bit of 

 experimentation with different kinds of fish. They exhibited 

 distinct differences in behavior in the presence of modified water. 

 He inclines to the belief that the changes in activity are due to 

 physiological conditions in many cases connected with C0 2 

 relations and do not necessarily involve associative memory at 

 all. The stimuli which gave rise to the modifications most 

 quickly are those most commonly encountered by the fish in 

 water — a disturbance of neutrality either in the direction of 

 acidity or alkalinity. 



INSTINCTS AND HABITS 



Mammals. — In the hope of coming to a better understanding 

 of abnormal human sexual behavior, Hamilton (10) has made 

 an excellent study of sexual behavior in monkeys. The obser- 

 vations included twenty animals mature, immature and eunuchs 

 and were made under the varied conditions of confinement and • 

 free range which a California laboratory permits. For the many 

 suggestive details the original paper must be consulted. The 

 author regards behavior as an expression of reactive tendencies 

 which have specific representation in structure. He says, "The 

 essential factors in the behavior phenomena are (a) the action 

 of a physiological process usually operating in conjunction with 

 environmental forces, in the production of (b) hungers which 

 impel the individual to manifest (c) activities, the particular 

 types or modes of which are to be ascribed to (d) specific organic 

 properties (reactive tendencies)." He recognizes three hungers 

 which normally impel the macaque to manifest sexual behavior, 

 viz: hunger for sexual satisfaction, hunger for escape from danger 

 and possibly hunger for access to an enemy. 



