506 ACTION OF NICOTINE ON SQUID 



action, it seemed of interest to determine further whether nicotine 

 is equally active on the stellar and cerebral ganglia of squid. For 

 this purpose the freshly hatched animals were immersed in sea water 

 solutions of Kahlbaum's alkaloidal nicotine. Typical effects were ob- 

 served with dilutions as great as 1:5,000,000, but stronger concen- 

 trations were found to be more satisfactory since they gave prompter 

 results. It was noted also that ordinary commercial preparations of 

 nicotine gave results identical with those of the purified alkaloid. 



Upon being put into a solution of nicotine in sea water, the squid, 

 in 3 or 4 seconds, falls to the bottom of the dish, with mantle short- 

 ened and broadened, quiescent, chromatophores relaxed, but with 

 head drawn in and chromatophores of head and tentacles extended. 

 After several minutes a secondary effect appears. If the dish is 

 tapped, head and mantle are extended, accompanied by muscular 

 spasms and maximum play of chromatophores over the entire body, 

 while ink is often shot. 



In order to determine whether the action of nicotine in producing 

 such mantle spasms is due to its action on the head or mantle gang- 

 lia or both, experiments were carried out with decapitated mantles. 

 These showed neither spasms nor play of the chromatophores, whether 

 the decapitation took place before or after placing them in the 

 nicotine solution. In order to remove any doubt in the matter, 

 animals were kept in the solution of the alkaloid until the mantle 

 spasms had developed, and were then decapitated, with the result 

 that the mantles immediately relaxed and the chromatophores closed. 

 Since in control experiments, in which decapitated mantles were 

 immersed in sea water containing strychnine or camphor, spasms 

 and chromatophore extension occurred, it is necessary to conclude 

 that nicotine produces mantle spasms by acting upon the cerebral 

 ganglion alone. 



In a sea water solution of nicotine 1 : 500,000 the mantle spasms 

 develop after 6 to 7 minutes at 24°C. It made no dift"erence in the 

 time required for the onset of this effect whether the animals were 

 removed from the solution and put into the sea water at the end of 

 1, 2, 3, 4, or 5 minutes or simply remained in the nicotine solution; 

 the spasms in all cases appeared promptly 6 or 7 minutes after im- 

 mersion in the poison. This somewhat astonishing result may be 



