ACCORDING TO BHESCIIET AND ROUSSEL DE VAUZEME. 429 



To see these well with the microscope, it is necessary to have 

 a piece of fresh skin well injected with blood. There is then 

 to be seen at the base of the dern), little reddish glands, irregu- 

 lar on the surface and grooved by blood-vessels. They are 

 enveloped in cellular membrane and surrounded by a multi- 

 tude of minute adipose vesicles. From the top of each of these 

 glands as seen in fig. 114, passes up a duct, which opens on 

 the upper surface of the derm in the grooves between the pa- 

 pills. JNIany capillary vessels adhere to the tube and the 

 gland, and a vessel of considerable size enters the base of the 

 latter. Tlie mucous matter thrown on the surface of the derm 

 by these organs, quickly unites with a coloring matter, from 

 which results the difierent tints of the corneous or epidermic 

 substance, hair, nails, scales, feathers, etc. in man and other 

 animals. This coloring is formed by the 



Cromatogenoiis* Apparatus, (see fig. 114,) 



— which is placed at right angles to the ducts of the mucous 

 glands, at the upper surface of the derm, and at the bottom of 

 the grooves. Its structure is parenchymatous or spongy. On 

 its under surface, it receives a great number of minute capillary 

 vessels, which is the outer limit of the vascular system, with the 

 exception of the vessels which pass up into the villi. On its 

 surface arises many short ducts, and which open in the grooves 

 between the papillce, to convey up the coloring matter in the 

 form of small granules to mix with the mucus.f When this 

 tissue is torn, a great many small filaments are seen (a,) from 

 which escape small scales or colorless corpuscles in great 

 quantities, (h, c.) This reservoir of scales is found in no other 

 part of the derm. 



— At/jis seen the fluid state of the corneous matter — that is 

 to say, the pigment of the scales floating in the midst of the 

 mucus. At g, couches of this matter, hardened and stratified, 

 to the right and left as they approach the surface, form the 



* From xP'^t"^' color, and yevnao), to create. — ?. 



f The coloring matter as is very obvious in the black, is now found lo be 

 deposited in delicate hexahi3edral cells which are cMed pigmentar?/ cells. In the 

 choroid coat of the eye the cells are arranged in several layers over each other, 

 so as to form a pigmentary membrane, the surface appearing perfectly black. 



