Cataleptoid Reflexes in the Monkey. 411 



nerve-trunks, the comparison of sensory overlapping with motor 

 overlapping, the relation of overlapping to acuteness of sensation : 

 individual variation, its extent and frequency, as far as can be judged 

 from the skin-fields. Comparison between the human bracbial plexus 

 and that of Macacus is made, and it is pointed out that the human 

 plexus is slightly prefixed, as compared with that of Macacns. 



Finally, in Section IV, " shock," and various spinal reactions are 

 examined, especially with reference to their effects upon the size and 

 other features of the areas of the root-fields, &c., and the results 

 collated and discussed. 



" Cataleptoid Reflexes in the Monkey." By C. S. SHERRINGTON, 

 M.A., M.D., F.R.S., Holt Professor of Physiology, University 

 College, Liverpool. Received December 29, 1896, Read 

 January 21, 1897. 



A phenomenon came under my observation in the course of experi- 

 ments upon monkeys at the commencement of the present year 

 which seems sufficiently interesting to merit record here. Its occur- 

 rence, so long as certain conditions of experiment are maintained, 

 appears regular and predictable. 



Although the character of the movements executed by the skeletal 

 muscles when excited reflexly through the medium of the isolated 

 spinal cord is variable, one feature common to them is their compara- 

 tive brevity of duration. Many of them are, as pointed out by Fick 

 and by Wundt years ago, hardly distinguishable in several particu- 

 lars from the simple twitches elicitable from an excised muscle, so 

 brief and local and inco-ordinate do they appear to be. Others are 

 more prolonged, and, as I have described in a paper recently com- 

 municated to the Society, exhibit various forms of sequence or 

 "march" (Hughlings Jackson). Without recapitulating the con- 

 clusions there drawn from the data given in that paper, I wish here 

 to merely point out that of movements due to purely spinal reflex 

 action, although some are fairly extensive, most are quite short- 

 lasting, and not so prolonged as the longer of those that can be 

 elicited under appropriate conditions from the cortex cerebri ; also 

 that if prolonged they, like the final phase of prolonged movements 

 initiated from the cortex, tend to become clonic, or to exhibit that 

 kind of action which in the paper referred to above I have desig- 

 nated "alternating." 



The reflex movements, the subject proper of this note, are, on the 

 contrary, of extremely prolonged duration, and absolutely devoid of 

 clonic character and of alternating character. If the cerebral hemi- 



