282 C. D. SXYDER. 



nerve-cord which directly connect the ganglia. In short, coor- 

 dinated locomotion is secured without the nerve cord, as such, 

 coming into play at all. In their passage the nervous impulses 

 involved, according to this conception, do not follow a straight 

 path with side-paths at each segment, but rather follow a path 

 which may best be described as a line of loops. 



Friedlander concluded that locomotor movements in the earth- 

 worm should not be regarded as the result of a single impulse 

 (say of the anterior segment) which passes through the length of 

 the body, but rather should it be regarded as the result of im- 

 pulses given off by each segment separately. 



2. That coordinated movements in animals higher than worms 

 may be set up and maintained, with the spinal cord brought into 

 use only in spots, as it were, rather than as an entire and single 

 organ, has been recently demonstrated in a remarkable way by 

 the experiments of Phillipson. 1 



It has been known for sometime 2 that, if a dog with a sectioned 

 cord be supported so that its hind legs hang freely in space, the 

 legs spontaneously begin an alternate flexor-extensor movement. 



Phillipson obtained this so-called pendulum movement of the 

 legs in a dog with sectioned nerve-cord. The movement lasted 

 sometimes for more than an hour ; it could be accelerated into a 

 veritable gallop by gently pulling the tail of the animal. The 

 valuable part of this experimenter's work, however, lies in the 

 complete analysis which he was able to make of the various steps 

 involved in the process of locomotion. From his experiments 

 and observations on this dog with the severed nerve-cord, he 

 drew conclusions concerning locomotion in the hind legs of 

 normal dogs somewhat as follows : 



The hind-foot of a dog during extension gently comes in con- 

 tact with the ground ; this foot-contact produces a feeble excita- 

 tion which brings on a flexing of the metatarsals with the sole 

 of the foot supported against the ground. The resistance of 

 the ground against this flexing of the metatarsals produces a 

 sensory-motor wave which brings a sudden halt to all muscular 



Phillipson, Maurice, Comptes Rtndus, Vol. 136, p. 6l, 1903. 



2 Freusberg, Arcliiv f. die ges. Physiologie, "Reflex Bewegung beim Hunde. , " 

 1874, Bd. IX., s. 358. 



