V ANIMAL AUTOMATISM 215 



being imperfectly elastic, does not return to exactly 

 its previous condition, but remains more distensible 

 tli an 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 per- 

 manency 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 " ruuta- 

 tiones," 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 "muta- 

 tiones" the picturesque name of vestigia renim, 

 " qua3 non in mente sed in ipso corpore et in 

 medulla quidem cerebri ineffabili modo incredi- 

 biliter minutis notis et copia infinita, inscriptse 

 sunt." 1 I do not know that any modern theory of 

 the physical conditions of memory differs essen- 

 tially 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 of the high probability, that every 

 molecular change which gives rise to a state of 

 1 Haller, Primce Linece^ etL iiu Senms intcrni, tllvii. 



