100 STRYCHNINE REACTION 



structure. It has been shown that strychnine causes hyperirritabihty 

 in the starfish.'' Proof that inhibition is reversed, i.e., converted 

 into an excitation, may be obtained by observing a strychninized 

 starfish (strychnine sulfate 1 : 10,000) in its attempts to right itself. 

 All of the arms take hold and retain their attachment to the bottom 

 (Fig. 2), finally resulting in the knotted situation shown in Fig. 3. 

 The usual inhibitory impulses which make the righting possible are 

 no longer eft'ective; all of the arms twist so that the tube feet maintain 

 their hold on the bottom. Strychnine has reversed the normal 

 inhibition. 



SUMMARY AND CONCLUSIONS. 



Two cases have been described, that of the marine planarian 

 Bdelloura and that of the starfish Asterias forhesii, in which strychnine 

 reverses reciprocal inhibition. These facts indicate that the nervous 

 systems of these invertebrates function in a manner similar to those 

 of the earthworm and vertebrates. Moreover, it would seem that 

 strychnine acts upon some chemical component of the neuron which 

 is always present in synaptic structures but which also occurs in the 

 simpler neurons of lower forms. The fact that strychnine is without 

 this characteristic effect on such forms as medusa and sea anemone, 

 indicates that the nervous systems of the starfish and planarian have 

 chemical affinities with the vertebrates which the coelenterates do 

 not possess. 



* Moore, J. Pharm. and Exp. Therap., 1916, ix, 167; Proc. Nat. Acad. Sc, 

 1917, iii, 601. 



