IO ANTS AND SOME OTHER INSECTS. 



are nevertheless partially modified and partly kept within due 

 bounds through the interference of the higher cerebral activities. 

 The enormous mass of brain-substance, which in man stands in no 

 direct relation to the senses and musculature, admits not only of 

 an enormous storing up of impressions and of an infinite variety of 

 motor innervations, but above all, of prodigious combinations of 

 these energies among themselves through their reciprocal activities 

 and the awakening of old, so-called memory images through the 

 agency of new impressions. In contradistinction to the compul- 

 sory, regular activities of the profoundly phyletic automatisms, I 

 have used the term "plastic" to designate those combinations and 

 individual adaptations which depend on actual interaction in the 

 activities of the cerebrum. Its loftiest and finest expression is the 

 plastic imagination, both in the province of cognition and. in the 

 province of feeling, or in both combined. In the province of the 

 will the finest plastic adaptability, wedded to perseverance and 

 firmness, and especially when united with the imagination, yields 

 that loftiest mental condition which gradually brings to a conclu- 

 sion during the course of many years decisions that have been long 

 and carefully planned and deeply contemplated. Hence the plas- 

 tic gift of combination peculiar to genius ranks much higher than 

 any simpler plastic adaptability. 



The distinction between automatism and plasticity in brain- 

 activity is, however, only a relative one and one of degree. In the 

 most different instincts which we are able to influence through our 

 cerebrum, i. e., more or less voluntarily, like deglutition, respira- 

 tion, eating, drinking, the sexual impulse, maternal affection, jeal- 

 ousy, we observe gradations between compulsory heredity and plas- 

 tic adaptability, yes, even great individual fluctuations according 

 to the intensity of the corresponding hereditary predispositions. 



Now it is indisputable that the individual Pithecanthropus or 

 allied being, whose cerebrum was large enough gradually to con- 

 struct from onomatopceas, interjections and the like, the elements 

 of articulate speech, must thereby have acquired a potent means of 

 exploiting his brain. Man first fully acquired this power through 

 written language. Both developed the abstract concept symbolised 



