RED 

 LIGHT 





y^> 



^ W 



^ Vkeratin 



Figs. 1, 2, 3. Reactions of ameba (Amoeba proteus, Leidy) to white 

 light, keratin, and red spectral light. The arrows indicate the direction 

 of protoplasmic streaming. Natural size of amebas, about 0.25 mm. long. 



Fig. 1. Reaction of an ameba to a small beam of white light. The ten- 

 dency was at first to move away from the perpendicular beam of light, 

 stages 1, 2, 3, 4. Positive behavior then set in and the ameba moved in a 

 curved path into contact with the beam, stages 5 to 10. The ameba partly 

 surrounded the light, then moved off. 



Fig. 2. Illustration of an ameba encircling a grain of horn (keratin). 

 Although pseudopods were formed at 8 and 10, leading away from the 

 horn, nevertheless the ameba moved around the test object about 270 

 degrees. By an oversight stages 3 and 4 were repeated in 5 and 6. 



Fig. 3. Illustration of an ameba partly encircling a beam of red spec- 

 tral light. 



