592 INTEGUMENTARY SYSTEM 



frogs and lizards are due to this type of chromatophoric behavior. The slower 

 changes of color in other amphibia and fishes also are due to this type of 

 chromatophoric activity. It thus appears that dermal chromatophores are re- 

 sponsible largely for the color effects found in the lower vertebrates. On the 

 other hand, in the bird group and in mammals, the chromatophores present 

 are mainly of one type, known as a melanophore. Melanophores produce pig- 

 ments, known as melanins (Dushane, '44, p. 102). The melanin granules, 

 elaborated by the bird melanophore, have a wide range of color from yellow 

 through orange to reddish-brown to dark brown. The melanophores in the 

 bird deposit the melanin-pigment granules within the feather as it develops 

 (fig. 271C). Melanophores also deposit melanins in the bill of the male sparrow 

 at breeding time under the influence of the male sex hormone (Witschi and 

 Woods, '36). Hair color in mammals is due, mainly, to pigmented granules 

 deposited in the hair by melanophores. The skin color of various races of 

 the human species is determined largely by the amount of melanin deposited 

 within the lower epidermal layers by melanophores resident in the upper 

 dermal area. In other words, the color of the skin and its appendages in the 

 higher vertebrate groups is due, to a considerable extent, to diffuse granules 

 deposited in the epidermis and epidermal structures by melanophores, whereas, 

 in lower vertebrates, dermal chromatophores are responsible for color pattern 

 and color change. 



b. Activities of Other Substances and Structures in Producing Color 



Effects of the Skin 



In the common fowl, the presence of carotenoids (lipochromes) in the 

 Malpighian layer (stratum germinativum) mainly is responsible for the color 

 of the face, legs, and feet. Orange-red, lipochromic droplets have been found 

 in the germinative stratum of the head of the pheasant, and these droplets 

 plus the capillaries in the dermis produce a brilliant red coloration (Dushane, 

 '44, p. 102). The color of the combs and wattles of the common fowl is con- 

 ceded generally to be due to the presence of a rich capillary plexus in the 

 dermis alone. In the ear regions of the fowl, the blood capillaries are reduced 

 in the dermis, and the presence of certain crystals of unknown chemical 

 composition produces a double refraction of the light waves. Hence, the ear 

 region appears white in reflected light. 



c. Genie Control of Chromatophoric Activity 



The transplantation of small pieces of epidermis and its adhering mesoderm 

 from one early chick embryo to another is possible. Under these conditions, 

 the donor tissue with its donor melanophores governs the color pattern of the 

 feathers developed in the area of the transplant (Willier and Rawles, '40). 

 That is, melanophores from a Black Minorca embryo, transplanted to a White 

 Leghorn embryo, will produce a Black Minorca color pattern, in the White 



