36 ANTS AND SOME OTHER INSECTS. 



tive activities, in combination with the faculty of gradually devel- 

 oping secondary individual automatisms (habits). 



The latter mode requires many more nerve-elements. Through 

 hereditary predispositions (imperfect instincts) of greater or less 

 stability, it presents transitions to the former mode. 



5. In social insects the correlation of more developed psychic 

 powers with the volume of the brain may be directly observed. 



6. In these animals it is possible to demonstrate the existence 

 of memory, associations of sensory images, perceptions, attention, 

 habits, simple powers of inference from analogy, the utilisation of 

 individual experiences and hence distinct, though feeble, plastic, 

 individual deliberations or adaptations. 



7. It is also possible to detect a corresponding, simpler form 

 of volition, i. e., the carrying out of individual decisions in a more 

 or less protracted time-sequence, through different concatenations 

 of instincts ; furthermore different kinds of discomfort and pleasure 

 emotions, as well as interactions and antagonisms between these di- 

 verse psychic powers. 



8. In insect behavior the activity of the attention is one-sided 

 and occupies a prominent place. It narrows the scope of behavior 

 and renders the animal temporarily blind (inattentive) to other 

 sense-impressions. 



Thus, however different may be the development of the auto- 

 matic and plastic, central neurocyme activities in the brains of dif- 

 ferent animals, it is surely possible, nevertheless, to recognise cer- 

 tain generally valid series of phenomena and their fundamental 

 laws. 



Even to-day I am compelled to uphold the seventh thesis 

 which I established in 1877 in my habilitation as privat-docent in 

 the University of Munich : 



"All the properties of the human mind may be derived from 

 the properties of the animal mind." 



I would merely add to this : 



"And all the mental attributes of higher animals may be de- 

 rived from those of lower animals." In other words: The doctrine 

 of evolution is quite as valid in the province of psychology as it is 



