296 CONCLUDING REMARKS. [Cuar. XV. 
when excited from a distance, send back some influence which 
causes the contents of the cells to become aggregated down 
to the bases of the tentacles. But the greatest inferiority of 
all is the absence of a central organ, able to receive impressions 
from all points, to transmit their effects in any definite 
direction, to store them up and reproduce them. 
