342 PHYSICAL EXPRESSION. 



of heated air; VII. Conduction; VIII. Cooling a 

 loss of motion ; IX. Law of diminution with the 

 distance ; X. Absorption of heat ; XIII. Discovery 

 of dark solar rays ; XIV. Dew. These are matters 

 concerning relations, time, quantity, visible pheno- 

 mena, etc. Such are the proper subjects of scientific 

 study, and such phenomena accompanying menta- 

 tion are capable of experimentation. I think, then, 

 that Professor Tyndall's remarks and his whole 

 work sustain the advisability of the work proposed 

 as a study of brain centres. 



Charles Darwin gave a biographical sketch of an 

 infant in Mind, 1877. The following extracts are 

 illustrative of our subject : 



"During the first seven days various reflex 

 actions, namely sneezing, hickuping, yawning, 

 stretching, and of course sucking and screaming^ 

 were well performed by my infant. On the seventh 

 day, I touched the naked sole of his foot with 

 a bit of paper, and he jerked it away, curling at the 

 same time his toes, like a much older child when 

 tickled. The perfection of these reflex movements 

 shows that the extreme imperfection of the volun- 

 tary ones is not due to the state of the muscles or 

 of the co-ordinating centres, but to that of the seat 

 of the will. At this time, though so early, it seemed 

 clear to me that a warm soft hand applied to his 

 face excited a wish to suck. This must be con- 

 sidered as a reflex or an instinctive action, for it is 

 impossible to believe that experience and association 

 with the touch of his mother's breast could so soon 

 have come into play. During the first fortnight he 



