AS HANDBOOK OF PHYSIOLOGY. 



Another theory of the development of the connective-tissue fibrils 

 supposes that they arise from deposits in the intercellular substance and 

 not from the cells themselves; these deposits, in the case of elastic fibres, 

 appearing first of all in the form of rows of granules, which, joining to- 

 gether, form long fibrils. It seems probable that even if this view be 

 correct, the cells themselves have a considerable influence in the pro- 

 duction of the deposits outside them. 



Functions of Areolar and Fibrous Tissue. The main function 

 of connective tissue is mechanical rather than vital: it fulfils the subsid- 

 iary but important use of supporting and connecting the various tissues 

 and organs of the body. 



In glands the trabeculae of connective tissue form an interstitial 

 framework in which the parenchyma or secreting gland-tissue is lodged : 

 in muscles and nerves the septa of connective tissue support the bundles 

 of fibres which form the essential part of the structure. 



Elastic tissue, by virtue of its elasticity, has other important uses: 



Fig. 48. Ordinary fat cells of a fat tract in the omentum of a rat. (Klein.) 



these, again, are mechanical rather than vital. Thus the ligamentum 

 nuohie of the horse or ox acts very much as an India-rubber band in the 

 same position would; being stretched when the head is lowered for 

 feeding or other purposes and aiding the muscles materially afterward 

 by its contraction, in raising the head to its normal position and keeping 

 it there. 



(o.) Adipose Tissue. 



Distribution. In almost all regions of the human body a larger or 

 smaller quantity of adipose or fatty tissue is present; the chief excep- 

 tions being the subcutaneous tissue of the eyelids, penis, and scrotum, 

 the nymphse, and the cavity of the cranium. Adipose tissue is also absent 

 from the substance of many organs, as the lungs, liver, and others. 



Fatty matter, but not in the form of a distinct tissue, is also widely 

 present in the body, e.g., in the liver and brain, and in the blood and 

 chyle. 



Adipose tissue is almost always found seated in areolar tissue, and 

 forms in its meshes little masses of unequal size and irregular shape, to 

 which the term lobules is commonly applied. 



