MUSCULAR TISSUES 



by acid stains, such as eosin, (c) the 

 giant cells, which are very large, but 

 contain only one nucleus, (d) the 

 erythroblasts, which are nucleated 

 red blood-cells. In addition to these 

 the red marrow contains mast-cells, 

 fat-cells and osteoclasts, or multinu- 

 clear giant-cells. 



(2) Yellow bone marrow is formed 

 from red marrow by the infiltration of 

 fat-cells which convert it into adipose 

 tissue. When examined in section 

 yellow marrow resembles ordinary 

 fat-tissue, consisting chiefly of large 

 compressed spherical fat-cells which 

 are supported by a recticulum of con- 

 nective tissue. Yellow marrow is 

 found in all the adult long bones, ex- 

 cept at their extremities. 



The Muscular Tissues. 



The chief characteristic of muscu- 

 lar tissue which distinguishes it from 

 all other tissues is its marked contrac- 

 tility. This variety of tissue may be 

 divided into three large groups: (i) 

 Striated muscle, (2) cardiac muscle, 

 and (3) smooth muscle. 



(i) Striated or voluntary muscle 

 makes up the greater part of all the 

 skeletal muscles by means of which 

 all voluntary movements are made. 

 In addition to this, it constitutes the 

 walls of the abdomen, and a few of 

 the muscles connected with the mid- 

 dle ear, tongue, pharynx, larynx, dia- 



FIG. 1 6. Two fibers 

 of striated muscle, 



In which the contractile 

 substance, m, has been rup- 

 tured and separated from 

 the sarcolemma, a and j; 

 p, space under sarcolemma. 

 (From Yeo after Ranvier.) 



