No. 536] 



COLOR INHERIT AX CE 



461 



All the samples being taken from the same body region, 

 there is a very close correspondence in the number of 

 epidermal layers involved. 



Number 9: Here all the epidermal strata of cells are 

 pigmented. In the basal layer the cells are packed with 

 the yellowish brown spherical granules to such an extent 

 as partially to obscure the nucleus and cause the cell to 

 bulge. In the more superficial layers, the granules are 

 massed distally and more scattered proximal ly, the 

 nucleus appearing very prominently. In the cutis, chro- 

 matophores are abundant, their granules being similar in 

 shape, size and color to those of the basal epidermal layer. 

 These cells are always in the near vicinity of the blood 

 vessels. In the upper layers of the epidermis the pigment 

 granules become darker, finer and frequently of oblong 

 shape. These several differential features are ascribed to 

 the several factors of desiccation, pressure and keratiza- 

 tion that the containing cells undergo in their passage to 

 the exfoliating surface. The same explanation probably 

 (at least to some degree) applies to the invariably darker 

 bacillary pigment granules of the shaft of the hairs ap- 

 pearing in all of the sections of this first group. 2 In sec- 

 tions of child's scalp, however, both shaft and bulb contain 

 the same yellowish-brown granules as found in the skin, 

 the only appreciable difference being a considerable ir- 

 regularity in shape and size. It must be noted here that 

 not all the basal cells (though in negro skin the excep- 

 tions both in dermis and epidermis are rare) are equally 

 packed with granules. The optical effect of a small num- 

 ber of granules is a lighter shade of brown than that 

 given by a denser mass of identically colored granules. 



The objection may be raised that discrimination or lack 

 of discrimination between a darker and lighter pigmented 

 granule is the result of an interpretation where the " per- 

 sonal equation " may factor largely. It is not denied that 



