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



to " darkness " in eight minutes. In 12 minutes it appeared nar- 

 cotized, was removed to fresh sea-water for five minutes, and then 

 replaced in the camphor solution. Subsequently it gave very 

 marked " darkness " responses and less marked " light " reactions, 

 these continuing during 15 minutes. It was then transferred to 

 fresh sea-water and slowly recovered. No definite responses could 

 be detected during recovery. 



Camphor (i : 16000). A specimen, kept for two and one half 

 hours in the laboratory, was immersed. It appeared completely 

 narcotized within a few minutes. It was transferred to fresh sea- 

 water, and then replaced in the camphor solution. After repeating 

 this procedure again, it gave slight but definite " light " and " dark- 

 ness " responses. 



Menthol (half-saturated solution) produced in two specimens 

 complete paralysis within a few minutes. The animals became 

 absolutely limp, in marked contrast to the action of the other com- 

 pounds used, which ultimately produced rigidity. They were 

 transferred to fresh sea-water and slowly recovered. No illumi- 

 nation responses could be detected at any period of treatment. A 

 saturated solution produced an immediate " limp " paralysis. A 

 particularly large fish (eight inches long) immersed in a one fifth 

 saturated solution showed no apparent effect of any kind in 45 

 minutes. 



(>) Gastcrosteus williamsoni micro cephalus. - - Calif ornian 

 stiklebacks, caught when free swimming near the station wharf. 

 Under the conditions of experiment changes in intensity of illumi- 

 nation produced no effect on the normal fish. 



Benzene (1:1500). Three specimens were tested. One, 24 

 mm. long, gave distinct positive reaction to " darkness " in four 

 minutes. This consisted of flicks of the tail and forward move- 

 ments. During constant illumination at this stage the animal was 

 quiescent. After five and one half minutes the animal appeared 

 moribund, and on removal to fresh sea-water it did not recover. 

 ; ' Light '" did not produce definite responses at any period. A 

 second animal of similar size was completely narcotized in less than 

 two minutes. Some doubtful "darkness" responses were ob- 

 served. The third, somewhat larger (33 mm.) and more active, 

 gave " darkness " responses in from four to five minutes after 



