030 



EAYI\IOND PEARL 



this seems piiradoxical. The behaviour was as follows : — A 

 larfro diffusion area had beeu formed^ and a specimen was 

 stimulated to a weak positive reaction at a distance of about 

 twice its own length from the food (Fig. 29, 1). It passed 

 into the diffusion area, but did not give another positive reac- 



/ B 



Fig. 29.— Showing the reaction of ii plauariiin to a very weak food 

 stimulus. Letters as in l"ig. 28. 



tion when opposite the food, but instead glided by and away 

 from it. When it had gone some distance in this direction 

 it stopped and gave a very clear and characteristic positive 

 reaction, so far as the form of the reaction indicated, but 

 with the turn away from instead of lowai'ds the centre of 



