SENSORY REACTIONS OF CHROMODORIS ZEBRA 



299 



a heated tank was allowed to flow over various portions of the 

 surface. A delicate thermometer held in a position corresponding 

 to that of the part concerned was used to get some idea of the 

 temperature of the water stream. The current did not stimulate. 

 With sea-water at 40°C., the buccal veil seemed the most sensi- 

 tive part. The tentacles also gave good responses. The gills 

 likewise reacted locally to water of about this temperature. Not 



20 Z5 50 

 Temp./C. 



Fig. 7 Relation of the rate of the heart beat to temperature, in two indi 

 viduals, A and B. 



until water was used issuing from the tube at a temperature of 

 nearly 50° were well-defined reactions had from the 'rhinophores,' 

 the tactile irritation occasioned by the stream can hardly have 

 been very important in these experiments, since with the water 

 at a lower temperature issuing at the same rate the rhinophores 

 were not activated. 



Efforts made in this way to localize a 'cold' response were 

 quite unsatisfactory. The gills react to water at 9° to 10° by 

 weak contraction. 



