412 Prof. C. S. Sherrington. 



spheres bo carefully removed, e.g., from a monkey, with avoidance of 

 haemorrhage and of fall of body temperature, and if sufficient time 

 be allowed to elapse for subsidence in the animal of what may be 

 called immediate shock, movements can be evoked remarkably 

 different from those I have ever seen elicitable as purely spinal 

 or as cerebral reactions. If a finger of one of the monkey's 

 hands bo stimulated, for instance, by dipping it into a cup of 

 hot water, there results an extensive reflex reaction involving 

 movement of the whole upper limb. The wrist is extended, the 

 elbow flexed, the shoulder protracted, the upper arm being drawn 

 forward and somewhat across the chest. The movement occurs after 

 a variable and usually prolonged period of latent excitation. The 

 movement, although it may be fairly rapid, strikes the observer each 

 time as perfectly deliberate ; it is of curiously steady and "smooth " 

 performance. Sometimes it is carried out quite slowly, and then, as 

 a rule, the extent of it is less ample. The most striking feature of 

 the reflex is, however, that when the actual movement has been 

 accomplished the contraction of the muscles employed in it does not cease 

 or become superseded ly the action of another group, but is continued 

 even for ten and twenty minutes at a time. The new attitude assumed 

 by the limb is maintained, and that too without clonus or even tremor. 

 In the instance cited, namely, that of the fore limb, the posture 

 assumed suggests the taking of a forward step in quadrupedal pro- 

 gression, and in that posture the animal will remain for a quarter of 

 an hour at a time. 



The degree of, for instance, flexion assumed in the new posture 

 seems much dependent on the intensity and duration of the stimulus 

 applied. If the degree is extreme, the attitude of the limb may not 

 be maintained to its full extent for the time mentioned ; thus, the 



elbow, at first fully flexed, will in the course of a minute or so be 

 found to have opened somewhat. This opening can be often seen to 



occur per saltum, as it were, but the steps are quite small, and recur- 

 rent at unequal intervals of between perhaps a quarter of a minute 

 and a minute. After some relaxation from the extreme phase of the 

 posture has taken place, the less pronounced attitude, e.^.,semiflexion 

 at the elbow, may persist without alteration obvious to inspection for 

 ten minutes or more. Apart from the occasional step-like relaxations, 

 the contraction of the muscles is so steady as to give an even line 

 when registered by the myograph. A renewed stimulation of the 

 finger excites further flexion, which is maintained as before in the 

 way above described. The posture can be set aside without diffi- 

 culty by taking hold of the limb and unbending it ; the resistance 

 felt in the process of so doing is slight ; the posture thus broken down 

 is not reassumed when the limb is then released. 



Analogous results aro obtainable on the hind limb. Hot water 



