22O A. T. CAMERON AND C. H. O DONOGHUE. 



EXPERIMENTAL RESULTS. 



Experiments have been carried out with benzene, phenol, cam- 

 phor, and menthol. The benzene used was Merck's " highest 

 purity, crystallizable," the phenol and menthol were commercial 

 preparations. Two preparations of camphor were used : one, a 

 Japanese commercial product, M. P. 174 C. ; the second, a thrice 

 resublimed preparation with M. P. 173.5 C. The latter gave 

 somewhat more pronounced results. The menthol and camphor 

 solutions were made by dissolving them in about twice their weight 

 of absolute alcohol, and adding this to sea- water. The drug was 

 precipitated in finely divided form and saturation of the sea-water 

 followed rapidly. Tests with the same amount of alcohol in sea- 

 water gave completely negative results. Various strengths of 

 solution were used. These are indicated in brackets. The 

 changes in illumination were effected by means of an acetylene 

 lamp, which was suddenly shone on the vessel containing the 

 animals under observation, and suddenly screened or removed. In 

 the following account " light " signifies a sudden marked increase 

 of illumination, " darkness " a sudden marked decrease. The 

 animals were contained in large beakers, and sometimes in large 

 porcelain evaporating basins. 



A large number of marine species have been tested. These 

 were selected largely with an idea of ascertaining in how wide a 

 distribution of species the reflex could be obtained. Our choice 

 was to some extent restricted, however, since it was limited to the 

 species easily available. 



The experiments are arranged in the order of the species tested. 



i. C eel enter at a. Hydromedusa. Gonioncmus vert ens. A com- 

 mon jelly-fish found amongst the eel-grass (Zostera marina) near 

 the station at low tide. 



Benzene (1:2000) produced no effect. The animal contracted 

 normally after 15 hours. Light variations produced no discernible 

 effect. 



Camphor (resublimed, i : 16000) produced no effect. The ani- 

 mal was quiescent after two or three hours, but still contracted 

 when touched after 18 hours. Light variations produced no dis- 

 cernible effects. 



