428 H. p. KJERSCHOW AGERSBORG 



In general, the head is the most sensitive part of the body both 

 to tactile and chemical stimulation. The effect of acid gives an 

 almost constant result. Comparatively, the dorsal tentacles are 

 more sensitive than the oral tentacles to acids, and the tips of the 

 dorsal tentacles respond more definitely to this stimulus than do 

 the tips of the oral tentacles. Hermissenda opalescens gives a 

 positive reaction toward 2 M ethyl alcohol and a negative reaction 

 to 2 M methyl. That is, the organism would even suck the ethyl- 

 containing pipette, but avoid the methyl-containing one. Speci- 

 mens would eat readily cucumarian gonads treated with ethyl 

 alcohol and show no ill effects. One specimen w^hich ate 

 10 mm. of cucumarian gonads treated for 40 min. in 2 M 

 methyl, died before the next day. It was found that this species 

 would eat very readily various kinds of animal matter: jelly-fish 

 tentacles, gonads of sea-urchins (Strongylocentrotus drobachien- 

 sis), sea-cucumber (Cucumaria japonica), and of the sand-dollar 

 (Echinarachinus excentricus) , etc. The gonads of Cucumaria are 

 filamentous in nature and are readily measured quantitatively.^ 

 I treated, therefore, strings of gonads of Cucumaria japonica 

 in various chemical solutions: M 0.25 lithium chloride; M to M 

 0.5 sodium chloride; M 0.05 magnesium sulphate; M 0.10 sodium 

 sahcylate; sat. sol. quinine sulphate; 2 M glycerol; 2 M ethyl, 

 and methyl from 5 min. to ca. 6 hrs. Hermissenda showed a 

 marked difference in response to food thus treated in comparison 

 of the reaction to normal food, i.e., food which had not been 

 treated. And this difference corresponded somewhat to the 

 reaction when these chemicals were applied onto the surface of 

 the body. For example, the response to M 0.25 LiCl. is to all 

 parts of the body. Wlien presenting food to the animal treated 

 in this solution, it was found that the animal took to it as readily 

 as to untreated food. The response to M NaCl is — ^(see ex- 

 planation of sign) ; food treated in this solution was taken by the 

 animal from to 50 mm. in one minute. The exact results were : 

 Out of ten specimens, five of which were given food treated ten 



2 These strings (filaments) were on the whole ca. 1 mm. in diameter; the 

 exact volume was not computed. The amount later is indicated in mm. of the 

 gonadic filament. 



