RETINAL REFLEXES OF NARCOTIZED ANIMALS. 225 



sponses to " darkness " similar to those described for benzene. 

 The reactions to " light " were less certain. Some animals were 

 killed by five minutes' immersion. 



Menthol (half -saturated solution) caused almost complete nar- 

 cosis in 14 minutes, during which time there was some tendency to 

 curl up and to cling together. Transferred to fresh sea-water, 

 during the recovery period the animals appeared to give some 

 " light " and " darkness " responses, though these were less certain 

 than in benzene, and certainly less great. 



3&. Arthropoda. Crustacea. Pcracarida. 



Amphipoda. Camphor (i : 16000) produced no effect during 14 

 minutes on some specimens of a species found on eel-grass. 



Isopoda. Pentidotea wosnesenskii. A small isopod found on 

 eel-grass. Normal animals under the conditions of experiment 

 showed little response to " light " and " darkness." Occasional 

 " flicks " backward of head and antennae occurred, but could not be 

 related to illumination changes. 



Benzene (i : 2000) produced a definite effect in five minutes, the 

 " darkness " response being distinct, that to " light " much less, but 

 still observable. Tapping the vessel or the table on which it was 

 resting produced the same sort of response. The reactions per- 

 sisted for 30 minutes. They consisted of movements of the anten- 

 nae, " kicks " when the animals were on their backs, and, when on 

 their legs, these were extended simultaneously so that the whole 

 animal was lifted, and at the same time the opercula were " flicked." 

 The responses gradually lessened with time. The best were ob- 

 tained when the animal had been brightly illuminated for one or 

 two minutes, and then the source of bright light suddenly removed. 

 An immersion of from two and one half to three hours proved 

 fatal. 



Phenol (1:2000) gave similar "darkness" and tap responses 

 after 20 minutes. These were not so marked as with benzene, and 

 " light " responses were not observed. 



Camphor (resublimed, i : 16000) produced no effect in eight 

 hours, the animals appearing completely normal. A saturated 

 solution produced no effect. 



Menthol (half -saturated solution) produced definite "light" and 

 "darkness" responses within 10 minutes. The animals were not 



