IX.] ANIMAL AUTOMATISM. 213 



Every boy who learns his lesson by repeating it 

 exemplifies the fact. Descartes, as we have seen, 

 supposes that the pores of a given part of the brain 

 are stretched by the animal spirits, on the occurrence 

 of a sensation, and that the part of the brain thus 

 stretched, being imperfectly elastic, does not return to 

 exactly its previous condition, but remains more dis- 

 tensible than it was before. Hartley supposes that 

 the vibrations, excited by a sensory, or other, impres- 

 sion, do not die away, but are represented by smaller 

 vibrations or " vibratiuncules," the permanency and 

 intensity of which are in relation with the frequency 

 of repetition of the primary vibrations. Haller has 

 substantially the same idea, but contents himself with 

 the general term " mutationes," to express the cerebral 

 change which is the cause of a state of consciousness. 

 These " mutationes " persist for a long time after the 

 cause which gives rise to them has ceased to operate, 

 and are arranged in the brain according to the order 

 of coexistence and succession of their causes. And he 

 gives these persistent " mutationes " the picturesque 

 name of vestigia rerum, " quae non in mente sed in 

 ipso corpore et in medulla quidem cerebri ineffabili 

 modo incredibiliter minutis notis et copia infinita, 

 inscriptsB sunt." 1 I do not know that any modern 

 theory of the physical conditions of memory differs 

 essentially from these, which are all children mutatis 

 mutandis of the Cartesian doctrine. Physiology is, 

 at present, incompetent to say anything positively 

 about the matter, or to go farther than the expression 



1 Haller, u Prirnaj LinesD," ecL iii. " Sensus Intend," dlviil 



