834 SCIENTIFIC RECORD FOR 1885. 



into the heart of psychology as a science; and the true course will be to 

 welcome all the new experiments for determining mental facts with pre- 

 cision, and to treat psychology as an acknowledged member of the sec- 

 tion. To this subdivision will then be brought the researches into the 

 brain, and nerves that deal with mental function; the experiments on 

 the senses having reference to our sensations; the whole of the present 

 mathematics of man, bodily and mental; the still more advanced in- 

 (juiries relating to our intelligence; and the nature of emotion as illus- 

 trated by expression." 



Instinct. — Mr. Romanes, in an address delivered before the Eoyal In- 

 stitution in 1884, and published in their proceedings for 1885, thus de- 

 fines instinct : " It is the nami^. given to those faculties of mind which 

 are coucernetl in consciously adaptive action prior to individual ex])er- 

 ience without necessary knowledge of the relation between the means 

 employed and the ends attained, but similarly performed under similar 

 and frequently recurring circumstances by all individuals of the same 

 species." The origin of instinct, according to the same author, is two- 

 fold : it is produced by lapsing intelligence or by natural selection. 

 The former is thus explained : " Just as in the lifetime of an individual, 

 adjustive actions, which were originally intelligent, may by frequent 

 repetition become automatic, so in the lifetime of the species, actions 

 originally intelligent may by frequent repetition and heredity so write 

 their effects on the nervous system that the latter is prepared, even 

 before individual experience, to perform adjustive actions mechanically, 

 which in jirevious generations were performed intelligently." For the 

 following reasons many instincts are referred to natural selection solely: 

 1. Considering the great importance of instincts to species they must 

 be in large part subject to natural selection. 2. Many instinctive 

 actions are performed by animals too low in the scale to admit of our 

 supposing that the adjustments which .are now intuitive can ever have 

 been intelligent. 3. Among higher animals intuitive actions are per- 

 formed at an age before intelligence, or the power of learning by 

 individual experience, has begun to assert itself. 4. Many instincts, 

 like incubation, are of a kind which could never have arisen by intelli- 

 gent observations," Finally, these two causes have cooperated in the 

 Ibrmation of instincts. 



The distance between intellection and volition on the one h and and 

 the organic processes associated with them seem to be narrowing year 

 by year. Dr. Horsely, in a lecture before the lio/al Institution of Great 

 Britain on the motor centers of the brain and the mechanism of the 

 will, omitting the discussion of the existence of the freedom of the will 

 .and the sources of our consciousness of voluntary power, arrives at the 

 following conclusions : 



As a rule, both cerebral hemispheres are engaged at once in receiving 

 and considering one idea. Under no circumstances can two ideas either 

 be considered or acted upon attentively at the same moment. Therefore 



