The Framework of the Body 23 



It will also be seen that the shaft is a hollow cylinder, 

 formed of compact tissue, enclosing a cavity called the 

 medullary canal, which is rilled with a soft, fatty substance 

 called the marrow of the bone. The mar- 

 row is richly supplied with blood vessels, 

 which enter the cavity through small open- 

 ings in the compact tissue. In fact, all 

 over the surface of bone are the openings 

 of minute canals leading into the substance. 

 One of these, especially constant and large 

 in many bones, is called the nutrient fora- 

 men, and transmits a special artery to 

 nourish the bone. 



Experiment 10. Obtain a part of a beef shin 

 bone, or a portion of a sheep's or a calf's leg, 

 including if convenient the knee joint. Have the 

 bone sawed in two lengthwise, keeping the marrow 

 in place. Boil, scrape, and carefully clean one-half. 

 Note the compact and spongy parts, shaft, etc. 



Experiment n. Trim off the flesh from the 

 second half. Note the pinkish-white appearance 

 of the bone, the marrow, and the tiny specks of 

 blood, etc. Knead a small piece of the marrow 

 in the palm ; note the oily appearance. Convert 

 some marrow into a liquid by heating. Contrast 

 this fresh bone with an old dry one. p IG I2 The Right 



NOTE.- While waiting for class use, fresh bones Femur sawed in 

 should be kept in a cool place, carefully wrapped 



in a cloth moistened with listerine, dilute carbolic ( Showin if arran S e ; 



ment of compact 

 acid solution, or even glycerine solution an ounce and cance n ous t i s - 



to one pint of water. sue.) 



34. The Periosteum. A fresh or living bone is invested 

 with a delicate membrane called the periosteum. It adheres 

 very closely to the bone, and covers every part except at 



