276 NATURE AND MAN. 



justified in assuming that the axial cord (of which the cerebellum 

 seems to be an appendage) furnishes the mechanism of automatic 

 action, the cerebrum is the instrument of the intelligence. And 

 experiment not only bears out this conclusion, but also demon 

 strates that a great number of actions which man requires long 

 training to be able to perform which training involves the 

 conscious purposive effort of the Ego are provided for in the 

 lower animals by the automatic mechanism which they con- 

 genitally possess. 



Among the lower vertebrates, the frog is the animal whose 

 actions have been most thoroughly studied, and their mechanism 

 most carefully investigated. These actions are for the most part 

 very simple ; the habits of the creature leading its natural life 

 being for the most part such as mechanism will readily provide 

 for. That to a very large extent they are purely automatic, can 

 be demonstrated by experiments of the kind already cited. Thus, 

 at the season of sexual excitement, the fore-legs of the male tend 

 to close firmly upon anything .that is placed between them (just as 

 mechanically as the fly-trap of the Dio?i&amp;lt;za closes upon the unlucky 

 insect that alights upon it), and will retain that clasp for weeks ; 

 and this although the spinal cord has been divided both above 

 and below the segment from which the nerves of the fore-legs are 

 given off. The clasping action may be excited by simply touching 

 the thumb of either fore-foot, which at that season is considerably 

 enlarged and furnished with a peculiar papillary structure ; and 

 thus it becomes obvious that this action no more indicates inten 

 tion, than does the corresponding movement of the fore-legs of 

 the Mantis. There are many other actions performed by the 

 agency of the spinal cord alone, which seem so purposive as 

 to make it difficult for those to regard them in any other light, 

 who have not been led by the considerations previously urged, to 

 recognize the large share which pure automatism has in the life 

 of this animal. If, again, its cerebellum be left in connection 

 with its spinal cord, the cerebrum and optic ganglia having been 

 removed, it will execute all its locomotive movements as well as 

 the complete frog would do, yet only in respondence to some 

 stimulus. Thus if, as it sits upright in the usual attitude of a 

 frog, the skin of its foot be pinched, it will jump; whilst,-if thrown 



