ACTIVITIES OF THE AMAROUCIUM TADPOLE 



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siderable magnitude, as is shown by the diagram (fig. 3) . When 

 observing the movements of a single tadpole, especially during 

 the period of its negative reaction to light, it is difficult to follow 

 the exact path and trend of its course, but, when working in a 

 dark-room with a large number of tadpoles in a rectangular dish 

 with electric light bulbs at opposite ends of the dish, the nega- 



Fig. 3 Showing three characteristic paths taken by tadpoles upon emerging 

 from the parent colony during exposure in a rectangular jar 12 cm. in width, 

 18 cm. in length, and 25 cm. in depth, to bright directive light reflected from a 

 south window, 12 feet distant, as seen from above. The sides of the jar, mo, 

 op, and pn, lined on the inside with black unglazed paper. I and II, Amaroucium 

 colonies on the bottom of the jar. a, b, and c, points at which tadpoles emerged. 

 Dotted lines, paths taken by tadpoles. Arrows indicate width and direction of 

 beam of light. 



tive response of the group as a whole is strikingly definite and 

 immediate. The entire group moves slowly away from the 

 source of light, changing its direction the instant the source of the 

 light is reversed. 



The light-perceiving organ of the tadpole, composed of a series 

 of three lenses, a cup-shaped layer of pigment granules, and a 



