300 



HITCHCOCK'S 



ANATOMY 



Fig. 291. 



Parasites of the Sebaceous Glands, ci. Two seen in their ordinary position at the 

 Orifice of the Gland, b. Short Variety, c. Long Variety. 



tially consist of long tubes convoluted and twisted upon them- 

 selves, (Fig 293, p. 301), located just beneath the cor i urn, 

 several of which join to form an outlet, which passes through 

 the epidermis in a spiral manner, so that as it opens exter- 

 nally, a valve is made preventing the entrance of substances 

 from without, but allowing a ready exit to all substances to be 

 discharged externally. The size of the gland proper is about 

 T Vth of an inch in diameter, and that of the tube is about T i T) th 

 inch. The outlets of these tubes (Fig. 292, p, 301,) are called 

 the pores of the skin, and are somewhat larger than the diam- 

 eter of the tubes. The most remarkable fact, however, con- 

 nected with these glands, is their immense number in the sys- 

 tem. Each tube when straightened measures on an average one 

 fourth of an inch in length, and by actual count there are at 

 least 2,800 in every square inch of the body. (Fig. 293, 

 p. 301.) Now the number of square inches in a man of or- 

 dinary height is 2,500, which would make the number of 

 pores or openings about 7,000,000, or the whole length of 



525. What is the general outline of the sweat glands? What is their size ? How many 

 on every square inch of the body ? What is their aggregate length ? 



