280 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
those in which the light with the shorter wave-lengths in each pair 
proceeded from generator A, and those in which it proceeded from 
generator B. In this way it was hoped to eliminate possible errors in 
the working of the generators. However, though the results were, in 
the main, the same as those obtained with single monochromatic 
lights, it cannot be said that there is much evidence in favor of positive 
phototropism for the red light. There were, for each pair of lights, 
some movements toward both lights, with the larger percentage 
always to the blue, or to that light of a given pair which in the spec- 
65 60 55 50 45 40 
R 4 G B 
Fic. 4.— Curves representing the percentages of movements toward red when 
paired with the three other lights, when the lights are received through both the 
skin and the eyes ( ); through the eyes only (----); and through the 
Skinvonlliy;) (2.1 seers ). Wave-lengths as abscissae and percentages of movements 
as ordinates. Points marked on axis of abscissae are the positions of the wave- 
lengths of the middle band of each light. B = Blue; G = Green; R = Red; 
Y = Yellow. 
trum was nearer the blue. Even in the pairs in which red occurred, 
there were movements toward this light. But, when the lights with 
which red was paired were used singly, there were movements to the 
dark, that is, movements away from these lights. If the results 
obtained here are compared with those given in Table 1, and the 
curves shown in Fig. 3 compared with those shown in Fig. 4, it will be 
seen that the percentages of movements toward the red, when paired 
