62 ASA A. SCHAEFFER. 



REACTIONS TOWARD SOLID PARTICLES WHEN STIMULATED AT THE 

 SAME TIME BY BEAMS OF LIGHT OR OF DARKNESS. 



A grain of globulin was placed over a small beam of blue 

 spectral light, and arranged so that the illuminated globulin lay 

 in the path of an Amceba proteus 365. The ameba moved in 

 spatulate form directly toward the globulin-blue light until it 

 came into contact with the globulin, when a pseudopod appeared 

 on the right. The ameba however ingested the globulin in 

 typical manner and then quieted down over the blue light for 

 over twelve minutes. 



A grain of globulin was placed in the path of a proteus with a 

 beam of green spectral light between the ameba and the globulin 

 ~373- Through a pseudopod thrown out on the right the ameba 

 moved away from the light-globulin 374. The ameba then 

 broke up into four pseudopods of which the left one of the middle 

 pair became the main pseudopod. The ameba moved forward 

 through this pseudopod toward the globulin in a curved path* 

 apparently, so as to avoid the light, pushed the globulin ahead a 

 short distance, and then ingested it in an imperfect food cup. 

 This is an interesting experiment. The beam of green light 

 stimulated the ameba negatively when contrasted with the 

 globulin. The ameba made a detour around the light to get to 

 the globulin. This experiment should be compared with Figs. 

 1-13 in a recent paper (Schaeffer, '17^) in which very similar 

 behavior is recorded as an ameba moved toward a grain of 

 globulin with a grain of silicic acid lying immediately in front of 

 the globulin. 



A grain of globulin was placed to the left of a proteus with a 

 beam of green spectral light between the globulin and the ameba 

 386. The ameba moved forward a short distance, then bi- 

 furcated, the right prong being directed backwards while the 

 left prong was directed toward the globulin 388. The ameba 

 moved toward the light at first 389 but presently the tip of the 

 ameba broke up into two pseudopods. The one thrown out on 

 the right enlarged rapidly as it moved in a slight detour around 

 the light toward the globulin 392, 393. After rolling the 

 globulin along the surface for a short distance it was ingested in a 

 typical food cup. This experiment as well as the preceding, 



