SIGNIFICANCE OF SPINAL REFLEXES. 859 



preservative of the part whence they are initiated. The conjunctiva! 

 reflex closing the palpebral fissure, essentially a cutaneous and from the 

 broad point of view a spinal reflex, is similarly preservative of the organ 

 whence initiated. 



In some instances, however, preservation of the individual, rather 

 than of the organ, seems the key to the reflex spinal reaction. In many 

 cases, such an interpretation has been given to signs, that when examined 

 without prejudice, are of themselves quite equivocal. But in reflex 

 autotomy, where the organ is sacrificed and the individual is freed from 

 capture, there seems no other valid meaning. The preservative reflex 

 here seems to offer one of the strongest guarantees that there is some 

 solidarity in the spinal reflex creature, that it is still an individual, 

 that it has still some personality. 



The spinal reflexes significant of locomotion seem never to give 

 indication of any other locomotion than that of the most usual kind. 

 Thus they yield always a going forwards, not a going backwards. They 

 share markedly that character of purely spinal reactions of the skeletal 

 musculature, namely, feebleness as compared with the prototype. It 

 suggests itself that they may contribute chiefly toward preparatory 

 posture in readiness for onset of action executed by the musculature 

 under the driving of the higher centres. Thus the well-known reflex 

 spinal posture of the frog is flexion of the hind-limbs, with the extensors 

 of the joints taut and ready for spring. Again with the primary reflexes 

 from the pedal ends of the limbs of the mammal. These apparently 

 relate to progression walking. But they do not take the form of the 

 propelling stroke, the extensor push, that thrusts the body forwards. 

 On the contrary, they flex the limb and lift it from the ground. This is 

 no doubt the phase of the limb's movement in progression which requires 

 least of force ; it resembles in so far the expiratory phase preceding the 

 inspiratory of respiratory movement ; it may almost be likened to the 

 diastole of the heart ; and like both these it is preparatory for a succeed- 

 ing phase of greater muscular effort. That phase succeeds also in the 

 spinal animal, but it is less easy to obtain, and recovers from shock 

 less soon. The subject is speculative, but certainly in the assumption 

 and maintenance of posture pure reflex spinal reaction upon the skeletal 

 musculature plays an important part. 



In opining whether spinal reactions are conscious or not, the follow- 

 ing considerations arise. After total rupture across the spinal cord in 

 man, the reactions of the isolated portion are never conscious. Where 

 nervous reactions have to be studied entirely objectively, as in the lower 

 animals and in young children, a criterion that may be well taken as 

 test of their conscious character seems associative memory. 1 Associative 

 memory would seem to be a postulate for the very existence of per- 

 ception. Consciousness can be regarded as a sequence of processes, 

 namely, of ideas, and of states of passage between such. Where even 

 simplest ideas, i.e. raw perceptions are not, there cannot be conscious- 

 ness. Animal movements that are appropriate not only for an im- 

 mediate but also for a remote end indicate associative memory. The 

 approach of a dog in answer to the calling of its name, the return of 

 an animal when hungry to the place where it has been wont to receive 

 food, such movements may be taken as indicative of consciousness, 

 since they indicate the working of associative memory. Examined by 



1 Cf. J. Loeb, ArcJi.f. d. ges. Physiol., Bonn, 1894, Bd. Ivi. 



