THE INTEGUMENT, OR SKIN 



is freely supplied with, blood-vessels. Hence, a needle entering 

 it not only produces pain, but draws blood. It is closely 

 connected with the tissues below it, but may be separated by 

 means of a sharp instrument. The surface of the cutis is not 

 smooth, but covered here and there with minute elevations, 

 called papillae. These are arranged in rows, or ridges, such as 

 those which mark the palm and thumb ; their number is about 

 80 to the square line (a line being one-twelfth of an inch). 

 These papillce contain blood-vessels and nerves also, and are 

 largely concerned in the sense of touch; hence they are 



* abundant where the touch is 



most delicate, as at the ends 



of the fingers. 



5. The Nails and Hair. 

 These are modified forms of 

 the cuticle. The nail grows 

 from a fold of the cuticle at 

 the root, and from the under 

 surface. As fast as it is 

 formed, it is constantly being 

 pushed outward.* The rapidity 

 of its growth can be ascer- 

 tained by filing a slight groove 

 Yig. is on its surface, and noticing 



,&. TUB ROOT OP A HAIB HIGHLY MAGNIFIED now tne space between it and 



1, 2, 3. The skin forming the hair-sac. 4. Se- the TOOt of the nail increases, 

 baceous glands. 5. The hair-sac . . , 



in the course 01 a lew weeks. 



When the nail is removed by 



an accident, it will be replaced by a new one, if the root be not 

 injured. {Notes 2 and 6.) 



* The practice of biting the nails should be avoided not only because 

 of the ugly shape which is produced, but because it impairs the sense of 

 touch in the ends of the fingers. In paring the nails, let them remain long 

 enough to nearly cover the pulp of the finger. Avoid scraping either sur- 

 face of the nail ; do not injure the " quick." 



2. The Life of the Cells of the Body. "The life of the body is long 



5. What are the nails and hair ? The growth of the nail ? The rapidity of its growth ? 

 Accident to the nail ? 



