34 



MASS TISSUES. 



{d) Bone.— The cells 

 or bone-corpuscles form 

 a meshwork of finely 

 branched cells, anasto- 

 mosing in every direc- 

 tion, and the matrix con- 

 sists of concentric layers 

 or lamellae of calcareous 

 matter, producing a 

 hard, dense, supporting 

 tissue. 



Bone. 



-.-/^-J 



Bone, more highly magnified. 



(2) Muscular tissue. — The cells or fibres are aggregated 

 into masses, and each is usually elongated in the direction of 

 contraction. The property of contractility is concentrated 

 in them, and they may or may not show a cross striation. 

 In the higher types the whole cell is modified into a fibre, 

 but in Hydra^ Ascaris^ and other types, only a part of it is 

 so modified. 



Fig. 9. — Muscular Tissue. 



(After Howes) 

 I 2 



I. Transverse section of small muscle. 



2. Muscle-fibres. 



(3) Nervous tissue. — The primary nervous elements are 

 nerve-cells. These are commonly stellate (multipolar), but 

 they may have only one or two branches (unipolar or 

 bipolar). The branches pass from the cells to muscles, 

 or to sensory epithelium, and they form nerve-fibres. A 

 number of nerve-fibres aggregated together and enclosed 

 in a sheath form a nerve. 



