902 



THE SENSOBY APPARATUSES. 



the subcutaneous connective tissue, where they are surrounded by adipose cells). 

 They consist of a convoluted tube (or several tubuli produced by dichotomous 

 subdivision) embedded in the reticular layer of the derma, and form an elliptical 

 glomerule, generally lying obliquely to the surface of the skin in the Horse. The 



Fig. 486. 



Fig. 487. 

 d 



VERTICAL SKCTION OF THE SKIN TREATED WITH 

 A SOLUTION OF CAUSTIC SODA, showing the 



branches of cutaneous nerves, a, b, inosculate 

 incr to form a terminal plexus, of which the 

 ultimate ramifications pass into the papillae, 



excretory canal is a continuation of this glomerule, 

 and passes through the derma and epidermis in a 

 spiral manner. (The tube is lined with a single 

 layer of cubical cells containing pigment and 

 fat-granules, while its wall is formed of a delicate 

 ynembrana propria. In large glands, smooth muscu- 

 lar fibres are found between the memhrane propria 

 and the gland cells.) 



The blood-vessels form a very rich network in 

 the papillary layer of the derma, and also surround 

 the sebaceous and sudoriparous glands. The li/m- 

 phatirs are disposed like the capillaries. 



(The arteries arise from vessels in the underlying 

 fasciae, and pass vertically towards the surface, 

 forming three sets of capillaries — the deepest to the 

 adipose tissue, the next run round the sweat-glands, 

 the last — the terminals — form a net-work in the 

 stratum papiUare, which sends loops into the papillae 

 and small twigs into the hair-follicles and sebaceous 

 glands. The veins arise in the stratum papillare 

 from the loops in the papillse, and from the follicles 

 and sebaceous glands. 



The lymphatics form two capillary networks 

 — one of fine vessels forming narrow meshes in 

 the stratum papillare, below the blood-capillary 



network ; and one with wider meshes, in the subcutaneous tissue. Minute 

 lymphatics are also found outside the hair-follicles and the two sets of glands.) 



The nerves are aiTanged in two layers : one loosely distributed in the derma ; 



SUDORIPAROUS GLAND (MAGNIFIED 



40 diameters). 



a, a, Contorted tubes composing 

 the gland, and uniting in two^ 

 excretory ducts, 6, 6, which join 

 into one sjiiral canal that per- 

 forates the epidermis at c. and 

 opens on its surface at d; the 

 gland is embedded in fat vesi- 

 cles, e, e. 



