216 



the case of indiarubber, for which results were very variable. The results 

 seem to indicate a certain amount of persistence of impressions, when 

 the latter are received several times in succession at short intervals. 



The first impression which persists is one in the mouth region leading 

 to refusal of the pellet. 



As this is strengthened the sequence is further abbreviated, an in- 

 hibitory stimulus w^ould seem to proceed from the mouth to the tentacles 

 preventing them from gripping, when the stimulation due to contact with 

 the filter paper has passed from them to the mouth. 



A further point of interest is that what does persist seems to remain 

 the property of the tentacles affected, and of that part of the mouth 

 directly related to them. 



It does not appear to be a possession of the whole animal, for other 

 tentacles, on the opposite side for example^ can be tricked subsequently, 

 at any rate once or twice, before they too exhibit the inhibitory reaction. 



Apparently, however, the nervous connections are fairly continuous 

 all round the mouth for the inhibiting tendency is soon manifest in the 

 second region tried, and so on. A further indication of this continuity 

 of nervous connections, this time in the column, is the fact that, when 

 one side of the hase of Tealia is irritated, the opposite side often con- 

 tracts rapidly. In Tealia crassicornis impressions seem to persist more 

 readily than in Actinia^ material which has been found inedible will be 

 rejected by the tentacles after a very few repetitions of the experiment 

 at one day intervals. 



The responsiveness of tentacles in Tealia is also probably more 

 varied and delicate than in Actinia^ for example, they will refuse filter 

 paj)er soaked in acetic acid while those of Actinia will hold such paper, 

 though they contract somewhat at the same time. Different species and 

 individuals are very differently affected by acetic acid, but in several 

 forms contraction ensues when that substance is applied to the column. 

 This contraction is very rapid in Tealia^ and affects all but the tentacles 

 nearest the region stimulated, these latter being often very widely 

 expanded. 



We notice that the tentacles of Tealia may be somewhat more sen- 

 sitive to chemical stimuli than are those of Actinia^ though even this is 

 not sufficient to have probably meaning for the normal life of the 

 species. We have spoken of the persistence of impressions due to re- 

 peated contact of tentacles with filter paper, but this is only a very 

 temporary affair; all traces of the impression are lost if the animals are 

 allowed a 6 — 10 days respite, though we incline to fancy that they 

 »learn« more quickly from a second set of experiments than they did 



