PLATE 5 



EXPLANATION OF FIGURES 



Fig. 13 The adrenal glands of this horned toad were stimulated with a weak 

 faradic current. The melanophore pigment of the entire skin, with the exception 

 of that of the right hind leg, from which adrenin has been excluded bj^ a ligature, 

 has been contracted. Compare with figure 8, in which a similar effect has been 

 produced by excitement. X 1. 



Fig. 14 The left sciatic nerve of this horned toad was stimulated at the point 

 indicated by the threads, close to the trunk. As a result the left hind leg is slight- 

 ly paler than the right. Note particularly the pale patch on the thigh indicated 

 by the arrow. X 1. 



Fig. 15 Cutting the spinal cord of this horned toad has caused the posterior 

 half of the skin to remain dUrk while the anterior half has assumed a pale colora- 

 tion. The dividing line between the dark and pale areas is indicated by 

 arrows . XI. 



Fig. 16 An effect, similar to that illustrated in figure 15, which was produced 

 in this horned toad only when, in addition to the transection of the spinal cord, 

 the adrenal glands had been removed. X 1. 



332 



