THE BEHAVIOR OF THE LOWER INVERTEBRATES 401 



animal. The animal usually rids itself of the carmine very 

 quickly, by a more or less complete reversal of the direction of 

 its movement. Grains of carmine are sensed by the Amoeba 

 at a distance of at least 100 microns. The animals have a 

 similar power of sensing egg white, uric acid and India ink at 

 a distance. Daylight, acting continuously, has no effect on the 

 food reactions. There is no way of predicting the size and shape 

 of the food cup from the stimulating object alone. The author 

 is of the opinion that the ectoplasm and endoplasm (of the gran- 

 ular species studied) react to such things as carmine in an oppo- 

 site manner, the former being positive and the latter negative. 

 In another paper the author (44) gives an account of the behavior 

 of Amoeba to glass, carbon, tyrosine, egg albumen, peptone, etc. 



Torrey (45) gives an essay on the physiological analysis of 

 behavior. 



Walton (46) finds that in Paramoecium caudalum there is an 

 increase in the rate of locomotion in response to an increase in 

 illumination. In animals from non-conjugating lines, 85% gave 

 this response, whereas only 55% of those from conjugating lines 

 showed it. This response to increased light intensity is only 

 gradually effected, The response of a given specimen is the 

 same to a given illumination irrespective of the light intensity 

 to which the animal has been previously exposed, provided the 

 specimen is given time to adjust itself to the new intensity. As 

 has been the case with previous investigators, no evidence was 

 found of a directive or orienting effect produced by the light. 



According to Wenrich (47) Anodonta fluviatilis is sensitive to 

 very slight decreases but not to increases in illumination. Such 

 stimulation generally results in the closing of one or both siphons 

 (seldom in closing the valves) ; the exhalant siphon being more 

 sensitive than the inhalant. In continuing his work on some 

 18 marine species of bivalve mollusks, the author finds three 

 classes: ' (a) Those sensitive to both increase and decrease in 

 light intensity (e.g., Mya); and (b) those sensitive to decrease 

 only (e.g., Pecten) ; and (c) those sensitive neither to decrease nor 

 to increase (e.g., Cumingia)." There is a perfect correlation in 

 these species between sensitivity to light and the presence of 

 pigment in the epithelium of the sensitive area. Pecten gibbus 

 shows a vigorous reaction by closing the valves in response to 

 an upward moving white card over a black background. As the 



