FURTHER NOTES ON THE BEHAVIOR OF 

 GONIONEMUS 



MAX MORSE 



The following notes upon the response of this je]ly-fls]i, Goni- 

 onemus, to light supplement those published hy the a\ liter in the 

 Journal of Comparafive Neiirology mid I\v/ch<>l()(/!/ l-'^^'"' 16, 

 p. 450-456). All the experiments to be described were made in a 

 dark-room to which sunlight was admitted by means of a porte- 

 lumiere apparatus. The aquarium was 100 cm. long, 70 cm., wide 

 and 50 cm. deep. 



That light has a direcdy orienting cfTeet on the animal is seen 



the slit, Fig. 1, a, and was reflected vertically downward upon the 

 medusa, />, as it lay upon the bottom of the aquarium, ^bhe light 

 fell upon one side of the medusa only, so that unilateral stimula- 

 tion was pro<luce<l. The cvlinder of light was cm. in diameter 

 and d.erefore suflicicnt to cover one half of the b,..ly and the ten- 

 tacles belonging thereto, even when extended. Owing to the 

 diflicultvof determiniuu- detinitelv the redaction when the medusa 

 lay witii its apex downward, it" was in ea.'h ca>e turne<l over. 

 After one half of the bell had been illuminated for from T) seconds 

 to three minutes, the reaction occurre<l. ^bhe first movement 

 carried the medusa vertically tq)ward and it was only after it had 

 pulsated three or four times that its path v<'er(M! from the i)er- 

 pendicular. It might turn towards the light i Fig. I. hn or awav 

 from it <hh or be m> indefinite as not to b<- j)lace.l in either of these 

 categori.^s. The results of one lum.lred trials, upon ditferent iudi- 

 vi.luals in die nuiin. are appen.le<l; those marked "indefinite" are 

 the responses where the animal had lu.t moved far euou-h to be- 



The effect of unilateral stinmlation <.n a swinuning jelly-fish 



