66 



ANATOMY. 



matter, and are called pigment cells. The pigment in them exists in 

 the form of minute colored granules. Still larger scaly epithelium 

 cells, e, exist in the mucous membrane of the mouth, throat, and 

 gullet, where they lie in several layers or are stratified. This is also 

 the case on the inner surface of the eyelids, where the deeper cells, as 

 shown in Fig. 44, <?, 4, are round ; the next above them are oval or 

 compressed, 3; the next somewhat flattened, 2; and the superficial 

 ones quite thin or scaly, 1. In the epidermis, cuticle, or outer skin, 

 which is raised in blistering any part, the cells also exist in many 

 layers; they are quite flat, Fig. 43, g, on the surface only, where they 

 have a peculiar, dry, horny character. The appendages of the cuticle, 

 viz., the nails and hair, are also formed of modified epidermoid cells. 

 There is a peculiar kind of epithelium called spheroidal or glandular, 

 because its soft cells, often filled with granular matter, are roundish, 

 and are found in the glands, i. e., in the smallest or ultimate ducts of 

 glands (see Fig. 91): sometimes, as in the liver, the glandular epithe- 

 lium cells, Fig. 43, /, are compressed on all sides or polyhedral. 

 When the spheroidal epithelium joins any other variety, whether squa- 

 mous or columnar, the cells gradually change their shape accordingly, 

 and thus is formed the transitional epithelium. Another form of epi- 

 thelium is called cylindrical or columnar. Fig. 44, a, 5, from the 

 cylinder- or column-like shape and perpendicular arrangement of its 

 component cells. This kind is found in the stomach and on the little 

 projections, called villi, in the small intestine. The group, a, 1, Fig. 

 44, shows a single row of columnar cells attached at one end ; 2, six 



Fig. 44. 



Fig. 44. (Henle and Kolliker.) Various forma of epithelium cells, magnified about 200 diameters, ex- 

 cepting a, 1, which is less magnified, a, columnar epithelium from the surface of a villus of the small 

 intestine; 1, cells attached to a part of a villus; 2, six cells seen at their free ends ; and, 3, a single cell 

 viewed'sideways, showing the central nucleus, b, row of ciliated epithelium, and a single cell enlarged, 

 from one of the smaller air-tubes, c, stratified squamous epithelium from inner surface of the eyelid in 

 the calf, showing in mass and separately, 4, 3, 2, 1, the changes in form from the deep to the superficial 

 cells. <l, stratified columnar ciliated epithelium, with several detached cells from the mucous or lining 

 membrane of the trachea or windpipe. 



cells seen at their free ends; and 3, a single cell more highly magni- 

 fied : the outer ends of these are said sometimes to be finely channelled 

 or perforated. In certain situations, as in the air-passage through 

 the nose and throat, and in the air-tubes of the lungs, this columnar 



