TISSUES 



101 



become large and crowded upon each other, while the intercellular 

 elements become the less conspicuous part of the tissue. The blood may 

 also be considered as a connective tissue in which the intercellular 

 elements are all fluid and form the blood plasma in which the cells 



float. 



123. Muscular Tissues, — Muscular tissues have as their function 

 motion and locomotion. As befitting cells set aside for this purpose, 



Lacuna 



Havers/an cana! 



'Fiber bundle 



Fiber bundle 



Tendon cell 



Leucocyte 

 B 



Whiie 

 fiber 

 bundle 



Chondrin E Cartilage 

 cell 



Connective 

 tissue cor- 

 puscle 



Fig. 40. — Different types of connective tissues; somewhat diagrammatic. A, bone, 

 showing the haversian canals which transmit the blood vessels and nerves, and the lacunae, 

 which lodge the bone cells, or bone corpuscles (refer to Fig. S E). B, portion of subcuta- 

 neous areolar connective tissue, showing several tissue elements. C, fat. D, tendon in 

 longitudinal section, showing longitudinal fiber bundles and rows of cells crowded into the 

 space between them. E, section of cartilage with the cells lodged in spaces in the chondrin. 

 All highly magnified. 



they become more or less elongated or fiber-like. In some cases, in order 

 to secure a greater length of the contractile fiber, it is composed not of 

 one cell but of many, all united into a single fiber, which gives evidence 

 of its composite nature only by the fact that it contains many nuclei. 

 The protoplasm within these cells becomes organized in a very complex 

 manner and in such a way as to determine the direction in which con- 

 traction shall take place. All muscle cells perform their function by 



