208 G. H. PARKER 



was found by Fleure and Walton ('07, p. 217), namely that 

 Actinia and Anthea retract at temperatures above 22°C. If, how- 

 ever, Metridium is subjected to a gradual change of temperature 

 which eventually reached 36°C., it slowly loses its responsiveness 

 to mechanical and chemical stimuli and soon dies. The loss of 

 responsiveness begins at about 34°C., and is complete' at 36°C. 

 An animal kept a few minutes in sea water at 35°C. may be 

 touched repeatedly on the column near the pedal disc without 

 showing any response and may be eventually killed in alcohol 

 in an expanded condition. Animals which have thus been ren- 

 dered insensitive seldom recover but in the course of a day or 

 so die. 



So far as Metridium is concerned subnormal temperatures 

 have little influence on its responsiveness except possibly on the 

 rate. Supernormal temperatures, if quickly applied, induce gen- 

 eral contraction; if gradually applied and of sufficient intensity 

 (35°C), they bring about a condition of non-responsiveness that 

 quickly passes over without contraction into one of death. I 

 made no attempt to localize the receptors for differences of 

 temperature (if, in fact, this response is dependent upon recep- 

 tors) and I am, therefore, not in a position to confirm or deny 

 Nagel's statement ('94, p. 337) that the tentacles are the organs 

 concerned. 



Many observers in the past have noted that retracted sea- 

 anemones can be induced to expand by placing pieces of meat 

 or other food so near them in the water that dissolved materials 

 from this food are wafted to the animals. Pollock ('83, p. 474) 

 and Romanes, in consequence of such observations, were led to 

 assume the presence of the olfactory sense in these animals. 

 More recently this response to food has been observed in Me- 

 tridium by AUabach ('05, p. 37) and in Actinia by Pieron ('06 b, 

 '06 c). So far as Metridium is concerned, I can fully confirm 

 Allabach's statement. If into two large glass dishes of fresh 

 seawater many specimens of contracted Metridium are placed 

 and into one of these dishes is poured a small amount of juice 

 from a crushed Mytilus edulis, the sea-anemones in that dish 

 almost without exception will expand their oral discs in a very 



