462 



(fl) Amorphous substances may be in liquid form, as in the fluid of the 

 blood, which holds a vast amount of salts and nutritive matter in solu- 

 tion, or they may be in a semi-liquid condition, as the plasma which 

 infiltrates the loose meshes of connective tissue and lubricates the sur- 

 face of some membranes, or they may be in the form of a glue or cement, 

 fastening one structure to another, as a tendon or muscle end to a bone, 

 or again they hold similar elements firmly together as in bone, where 

 they form a stiff matrix which becomes impregnated with lime salts. 

 Amorphous substances again form the protoplasm or nutritive element 

 of cells or the elements of life. 



(h) Fibers are formed of elements of organic matter which have only 

 a passive function. They can be assimilated to little strings or cords 

 tangled one with another like a mass of waste yarn, woven regularly 

 like a cloth or bound together like a rope. They are of two kinds, white 

 connectivetissuefiberSjOnly slightly extensible, pliable, and very strong, 

 and yellow elastic fibers, elastic, curly, ramified, and very dense. These 

 fibers once created require the constant presence of fluids around them 

 in order to retain their functional condition, as a i)iece of harness 

 leather demands continual oiling to keep its strength, but they undergo 

 no cliange or alteration in their form until destroyed by death. 



(c) Cells, "which may even be regarded as low forms of life, are masses 

 of protoplasm or amorphous living matter with a nucleus and frequently 

 a nucleolus or living germs, which are capable of assimilating nutriment 

 or food, propagating themselves either into others of the same form or 

 into fixed cells of another outward appearance and different function, 

 but of the same constitution. It is simply in the mode of groui^ing of 

 these elements that mc have the variation in tissues, as: (1) loose con- 

 nective tissue ; (2) aponeurosis and tendons; (3) muscles; (4) cartilage; 

 (5) bones; (G) epithelia and endothelia; (7) nerves. 



(1) Loose connective tissue forms the great framework or scaffolding 

 of the body, and is found under the skin, between the muscles sur- 

 rounding the bones and blood vessels, and entering into the structures 

 of almost all of the organs. In this the fibers are loosely meshed 

 together like a sponge, leaving spaces in which the nutrient fluid and 

 cells are irregularly distributed. This tissue we tiud in the skin, in the 

 spaces between the organs of the body where fat accumulates, and as 

 the framework of all glands. 



(2) Aponeurosis and tendons are structures which serve for the ter- 

 mination of muscles and for their contention and for the attachment of 

 bones together. In these the fibers are more frequent and dense and 

 are arranged with regularity either crossing each other or lying parallel, 

 and here the cells are found in minimum quantity. 



(3) Muscles. — In these the cells lie end to end, forming long fibers 

 which have the power of contraction, and the connective tissue is in 

 small quantity, serving the passive purpose of a baud around the con- 

 tractile elements. 



