44 



COLOR CHANGES IN ANIMALS 



tissue, and through this connective tissue and the fin- 

 rays run the blood-vessels and nerves that supply the 

 tail. In this way the two layers of melanophores in the 

 tail are subtended by tissue rich in blood and lymph. 

 Yet when a dark caudal band fades, as has just been 

 pointed out, it does so not uniformly as though it were 



Fig. 32. Section of the integument of the caudal fin of the 

 catfish, Ameiurus^ showing two small spherical melanophores in 

 the epidermis and three large ones in the derma. Parker, Jour. 

 Exp. Z00L, 1934, 69, pi. 3, fig. 15. 



acted on from below by some constituent of the adja- 

 cent blood and lymph, but laterally as though it were 

 attacked at its edges. It can, however, be made to fade 

 uniformly by injecting into the circulation of a given 

 fish a small amount of dilute adrenalin, after which the 

 whole band will blanch evenly, the axis as rapidly as 

 the edges. 



Further evidence that the blood of a Fundulus does 

 not aid in blanching a band is seen in the fact that if 

 the defibrinated blood from pale fishes is injected into 

 a dark one no change in tint is seen in the recipient. 

 And the reverse is also true, namely, blood from a dark 

 fish has no effect upon the tint of a pale one (Matthews, 

 J 933)- The fading of a caudal band as ordinarily ob- 



