Reactions of jEolosoma to Chemical Stnnidi 57 



the pipette, after which the exploring reactior.s were exhibited as 

 before. The animal then moves away a; Varying angles. 



Organic Acids. The reactions were 'milar to the above. 

 Acetic acid always seemed further to sti;nulate an erection of the 

 more anterior setae. The reactions to citric acid were similar to 

 those with sulphuric acid. The puckering of the prostomium was 

 more marked with oxahc acid. 



Hydrates. It is very difficult to get a characteristic reaction 

 with the hydrates. The animals invariably turn awav from the 

 source of stimulation without giving marked evidence of the 

 exploring reaction. If the stimulus is repeated several times they 

 curl up and give no further movement. When left alone they 

 slowly resume normal activities. 



Carbonates. The animal gives a positive reaction in every case. 

 The exploimg movements were wxll marked, and were associated 

 with contractions of the pharynx as though feeding. 



Halides. The head is swayed slowly from side to side with a 

 rythmical motion. The peristaltic movements are markedly 

 accentuated by both the Na and the K solutions. The exploring 

 reaction was not in evidence. The animals make no effort to 

 move toward or away from the pipette. 



Sulphates. There is a positive reaction to FeSO^ in every case, 

 associated with the normal exploring movements of the anterior 

 segments. CuSO^ develops in ^Eolosoma reactions practically 

 identical with those of the mineral acids. With ZnS04 exploring 

 reactions are very slow, but the puckering of the prostomium is 

 more strongly marked. 



In all of these experiments, with the exception of the halides and 

 hydrates, it must be noted, that in the stimulations lateral to the 

 prostomium the animal first turns its head toward the side which 

 is stimulated. The normal exploring reactions were then 

 exhibited with the result that the animal finally moved toward or 

 away from the field of stimulation. ' 



Toxicity of Stimuli 



Were these movements correlated with the relative toxicity of 

 the elements used? To test this a number of iT-olosoma were 



