242 VETERINARY PATHOLOGY. 



eous pigmentation of animals, erythema, hemangiomata and other 

 pathologic processes are not as evident as like conditions in the 

 human. The excessive cutanecius pigmentation protects the skin 

 from the injurious influences of sunlight. 



Hair, wool, fleece, fur and feathers are variously colored, the 

 color depending upon the soluble pigment in the cortical portion 

 of the cutaneous appendages. The color of the skin is usually 

 an index to the color of the hair or similar epidermal appendages. 

 The color of hoofs, horns, and claws is probably dependent upon 

 cutaneous pigment. 



\'o!untarv muscle tissue is pigmented with varying quanti- 

 ties of hemoglobin, excepting the so-called white meat of fowls 

 (the sternal muscles and muscles of the pectoral archj. The 

 pigmentation of the ^■olunta^y muscles varies in the different 

 animals. The ecpiine muscles are the most intensely red, the 

 intensity of pigmentation in the muscles of other animals being 

 in the following order: bovines, ovines, porcines, canines, felines. 

 The flesh of duck and C|uail and the dark meat of other fowls is 

 darker even than equine muscle. Heart muscle is ver^- dark in 

 color because of the excessive quantities of pigment. Gizzard 

 muscle is intenseU- pigmented. Involuntary muscle of all ani- 

 mals is very light in color, because of the limited (|uantitv of 

 pigment contained. The significance of the pigmentation of 

 muscle is not known, possibly the hemogloljin of the muscle cell 

 has some impcjrtant metalxilic function. 



The mucous membrane, ])articularly of the mouth, is fre- 

 quently pigmented. The buccal mucous membrane of the sheep 

 and dog is often black. The uterine mucous membrance of 

 the Ijitch is occasionally c|uite black as a result of pigmentation 

 derived from the uterine glands, and no doubt is indirectly a 

 derivative of hemoglobin. 



Bones, especially the internal portion of the articular extremi- 

 ties, are frequently pigmented from the red marrow that occupies 

 the spaces in the cancellous bone. 



The liver and spleen are naturally deeply pigmented because 

 of the excess of free hemoglobin in those organs. The kidney 

 also appears pigmented, probably because of the excess quantity 

 of blood contained in it. The choroid tunic of the eye is deeply 

 pigmented with a substance not unlike melanin, the purpose of 

 which is to absorb rays of light. 



