

THE ACTION OF STRYCHNINE AND NICOTINE ON THE 

 NEUROMUSCULAR MECHANISM OF ASTERIAS. 



By a. R. MOORE. 



(From the Physiological Laboratory of Rutgers College, New Brunswick, N. J., and 

 the Marine Biological Laboratory, Woods Hole, Mass.) 



(Received for publication, October 23, 1919.) 



It has been demonstrated that strychninization in Asterias is fol- 

 lowed by extreme dorsal flexure of the rays and consequent inability 

 to make righting movements^ (Figs. 1, 2, and 3). This *' spasm" 

 position of the rays is accelerated and accentuated by sensory stimu- 

 lation. In order to determine the location of the muscles which 

 cause this action, the dorsal myodermal sheath is cut from all five 

 rays of a specimen of Asterias. This leaves only the ventral floors 

 of the rays attached to the central disk. When such a preparation 

 is put into a solution of strychnine in sea water, the dorsal flexure of 

 the rays takes place, although not so completely as in the intact 

 animal. This result shows that the ventral walls of the rays contain 

 muscles which act to bend the floor dorsally. The excised pieces of 

 dorsal myodermal sheath when strychninized show dorsal flexure. 

 Therefore, it is evident that in the intact animal, muscles of both 

 the top sheath and floor of the ray act together to flex the ray dorsally. 



The reverse picture for the entire animal may be obtained by 

 immersing small specimens of Asterias in a solution of alkaloidal nico- 

 tine in sea water, concentration 1 : 50,000. Within a few minutes the 

 rays bend downward at the tips and the central disk is raised (Fig. 4), 

 while at the same time the tube feet are completely shortened and 

 withdrawn. The ventral flexure increases in degree until the animal 

 is a compact mass (Fig. 5). At this point the starfish falls over on 

 its side, where it remains in the knotted condition shown, for 15 or 20 

 minutes, after which extension takes place. 



1 Moore, A. R., J. Gen. Physiol, 1918-19, i, 97. 



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