272 MANUAL OF HISTOLOGY. 



in the other layers. The next two or three strata consist of 

 more or less polygonal-shaped bodies, each with a spherical 

 nucleus. The cells of these layers are large, their contours 

 sharply defined, and they contain more or less pigment. It is 

 this substance deposited in the corpuscles that gives the charac- 

 teristic color to the different races of mankind. Their cell-bod- 

 ies are larger in proportion to the nucleus than in the first layer. 

 In the succeeding laj^ers the cells increase in size and are more 

 granular in appearance, the cells and nuclei become flatter as 

 they approach the granular layer, and, finally, lie with their long 

 axes parallel to the surface. The granular structure which in 

 the lowest layer is most marked around the nucleus, gradu- 

 ally extends toward the margin of the cells, as the surface is 

 approached, so that finally a clear area is seen around the 

 nucleus, whilst the remainder of the cell-body is markedly 

 granular. At the same time the cell-body becomes firmer and 

 the nucleus smaller. 



All the cells of the rete Malpighii, except those of the first 

 row, are united to each other by filaments (Martin, Bizzozero, 

 Heitzmann), the so-called prickles of Max 

 Schultze (Fig. 116). These uniting filaments 

 or bands vary much as regards their size 

 and length in different parts of the bod}'. 

 They are most distinct wherever the Mal- 

 pighian layer is well developed, but are 

 thicker and longer in the lower rows of 

 ceiis cells than in the upper. At the stratum 

 of the rete. x 1600. lucidum they cease to exist. Between 



neighboring corpuscles the length of these bands is in direct 

 proportion to the distance between the borders of the cell- 

 bodies. Hence, where three or four cells meet at one place, 

 as in the centre of Fig. 116, the minute filaments are much 

 longer than those uniting the bodies of closely adjoining cells. 

 Examining these prickle-cells with the microscope, alternate 

 dark and light bands are seen between the cell-borders. With 

 a low power, these light bands appear to consist of spaces be- 

 tween the connecting filaments, the dark lines being the con- 

 necting filaments, but with a high power the latter can be 

 recognized as spaces between the former. The light bands 

 can be traced from the surface of one cell to the surface of 

 another, whilst the dark lines are the spaces between these 



