618 SERGIUS MORGULIS 



Aii animal with a break in its nervous system somewhere about 

 the girdle remains, as a rule, quiet and motionless when placed 

 upon moist filter paper, but occasionally it takes to creeping; in 

 that case the movements of the anterior and posterior parts are 

 completely coordinated, though the injured portion takes no active 

 part in the movements. However, while the worm is inactive the 

 ''nerveless" portion may be touched or poked, treated with alco- 

 hol, hot water or an electric current without causing the least 

 disturbance to the other parts of the worm. It is true that local 

 muscular contractions may be produced by increasing the stim- 

 ulus, but the impulse is not transmitted to adjacent segments 

 which have the nerve intact. The local response of the muscula- 

 ture of a deficient segment may vary in intensity, but it never 

 induces the next segment to become active in a similar way. 



Apart from their bearing upon the question of the segmental 

 mechanism of the earthworm's locomotion, these data are likewise 

 significant from the point of view of the physiology of its nervous 

 system. The nervous system of the earthworm consists of cuta- 

 neous sensory cells and the ventral nerve-cord; sensory neurites 

 pass from sensory cells to the cord and motor neurites, emerging 

 from the latter, supply the muscles of the body. Golgi prepara- 

 tions of earthworm material show besides the neurites also den- 

 dritic processes, spreading out over the inner surface of the cutan- 

 eous epithelium and forming a sort of network. The function of 

 this network is unknown, and although my experiments yield no 

 final solution of this obscure question, the possibility that the net- 

 work is an organ for the transmission of impulses is apparently 

 excluded, since in none of the experiments was there ever an 

 indication of a transmission of stimuli across a break in the ven- 

 tral nerve-cord. 



Studying the reactions of an earthworm with the nerve-cord inter- 

 rupted in the region of the girdle, we find that moderate stimuli, 

 both mechanical and electrical, when applied to the head start 

 a contraction-wave running posteriorly, which ends abruptly as 

 soon as it reaches the break in the nerve-cord. Applying a stim- 

 ulus immediately anterior to the break in the nerve cord, a strong 

 constriction of the body-wall is produced near the "nerveless" 



