THE SELECTIVE ACTION OF NICOTINE ON THE CENTRAL 

 NERVOUS SYSTEM OF THE SQUID, LOLIGO PEALIL 



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, February 19, 1919.) 



Juvenile squid, Loligo pealii, are excellent indicators of the action 

 of neurophil alkaloids. Excitation is shown by spasms of the mus- 

 culature, in tentacles and mantle, and expansion of the chromato- 

 phores. This latter effect is caused by contraction of the radial 

 muscle fibers attached to the sac-Kke chromatophores. The cen- 

 tral nervous system of the squid is formed by the large cerebral 

 ganglion to which are connected by nerve strands the two mantle or 

 stellar ganglia. The musculature of the mantle may be excited 

 either by the activity of the stellar ganglia or by that of the cerebrum. 

 By means of observations on decapitated specimens it is thus pos- 

 sible to determine the seat of the nervous excitation. Strychnine in 

 concentrations as low as 1 : 500,000 causes the entire musculature to 

 show spasms, with accompanying extension of the chromatophores 

 in tentacles, head, and mantle. Since this occurs in decapitated as 

 well as in entire specimens, it must be concluded that strychnine 

 acts upon both groups of ganglia.^ Camphor acts in a similar way, 

 causing mantle spasms in decapitated animals, the excitatory action 

 of camphor on the stellar ganglia being thereby proven.^ 



Nicotine is said to have an action in vertebrates similar to that of 

 other excitants of the central nervous system.^ With respect to its 

 central action, this alkaloid falls in Maxwell's second group of brain 

 stimulants since it acts upon ganglia alone. ^ In view of this selective 



1 Baglioni, S., Z. allg. Physiol., 1905, v, 43. 



2 Moore, A. R., Proc. Nat. Acad. Sc, 1917, iii, 598. 



^ Meyer, H., and Gottlieb, R., Pharmacology, Philadelphia, 1914, 373. 

 ^ 4 Maxwell, S. S., Am. J. Physiol., 1918, xlvii, 283; /. Biol. Chem., 1907, 

 iii, 21. 



505 



