146 ELEMENTARY BIOLOGY. [CHAP. 



b. The mouths of the cutaneous gla?ids ; seen as 

 clear round spots, although their openings are 

 really triradiate : their number. 



ii. Preserve a piece of skin in alcohol of increasing 

 strengths, and stain with borax-carmine; imbed 

 and cut sections perpendicular to its surface : 

 mount in Canada balsam. Examine under a low 

 power. 



a. The epidermis ; the superficial thinner and deep 

 stained portion. 



/;. The dermis; the deeper main mass, for the 

 most part lightly stained. 



I. Pigmetit ; most marked as a conspicuous ir- 

 regular black layer, in the superficial stratum 

 of the dermis. 



d. Cutaneous glands ; seen in section as numerous 

 large oval, rounded, or flask-shaped spaces, lying 

 within the dermis. Many can be seen to open 

 on the free surface by a narrow neck. 



iii. Examine under a high power. 



a. The epidei'mis {stratified epithelium). Work 

 from within outwards ; there will be found in 

 order : 



a. The Malpighian layer ; composed of a usu- 

 ally single basal row of close-fitting columnar 

 cells, each with an oval nucleus ; and of a 

 superficial main mass, consisting of several 

 rows of rounded or oval cells whose long 

 axes are parallel with the free surface. Small 

 pigment granules are frequently aggregated 

 around the nuclei of the latter. 



