CUTANEOUS FOLLICLES OF THE TOAD. 259 



roramunicates with the skin : this opening is small, compared 

 with the size of the follicle, in the collapsed state of which it is 

 partially closed, in consequence of the approximation of the 

 folds of the internal membrane. This membrane, especially 

 in the larger follicles, is seen in a horizontal section to be 

 folded upon itself in a direction perpendicular to the surface of 

 the skin (figs. 3 and 4), so as to present a number of imperfect 

 septa projecting from the circumference of the follicle towards 

 the centre, with lateral depressions, or saculi, between them. 

 The whole of the internal surface of this membrane is lined 

 with epithelium, consisting of delicate, lozenge-shaped, very 

 flat cells (fig. 5), connected together by their edges, but pre- 

 senting each a very sharp and well-defined margin, and one 

 large nucleus. The nucleus contains minute granules, which, 

 as the cells degenerate into a state of decay, can be seen to in- 

 crease in size and distinctness, and ultimately to become broken 

 up into the minute oily-looking granules (fig. 1), of which the 

 secretion of the follicles is chiefly made up. Tlie vessels of 

 these follicles consist of capillaries of a larger size than those 

 forming the plexus on the surface of the skin, and with much 

 smaller areolae ; they do not follow accurately the folds of 

 membrane projecting into the cavity of the follicles, but 

 simply pass over, and on the outer side of these folds, so as to 

 encircle the entire sack with a single layer of capillaries. The 

 afferent and efferent blood-vessels of this plexus are connected 

 with its deep surface, which, being generally only two in 

 number, an artery and a vein, and give to the follicles, when 

 minutely injected, very much the appearance of a Malpighian 

 body highly magnified. 



These follicles are entirely surrounded with the white fibrous 

 tissue of which the skin is composed, excepting where they 

 open on the surface. These fibres are disposed in two 

 planes, one parallel with the surface, the other perpendicular 

 to it ; the former are by far the most numerous, and constitute 

 the chief thickness of the skin ; the latter are comparatively 

 few, and only partially distributed, being collected into bands 

 placed at nearly equal distances apart, which, extending through 

 the entire thickness of the skin, from its deep to its superficial 

 surface, draw, as it were, the fibres of the first set in these 

 situations more firmly together ; and thus producing a closer 

 approximation of the fibres, and a corresponding diminution 

 in the thickness of the skin at these parts, they cause the 

 horizontal cellular fibres to take an undulating course. 



Between the part of the true skin just described, and its 

 epidermic surface, and immediately beneath the cutaneous 

 capillaries, there is a laver of earthy matter, varying in thick- 



s 2 



