THE CONNECTIVE TISSUES. 



colorless, protoplasmic membrane, thickened at one point, in which a 

 nucleus can usually be detected. This membrane incloses a globule of 

 fat, which during life is in the liquid state. It is composed of olein, 

 stearin, and palmitin. The origin of the fat is to be referred to a 

 retrograde change in the protoplasmic material of the connective-tissue 

 cells. When this protoplasm becomes rich in carbon and hydrogen, 

 it is speedily converted into fat, which makes its appearance in the 

 form of minute drops in different portions of the cell. As the drops 

 accumulate, at the expense of the cell protoplasm, they gradually 

 coalesce, until there remains but a hin stratum of the protoplasm, 

 which forms the wall of the vesicle.U Adipose tissue may, therefore, 

 be regarded as areolar tissue, in which, and at the expense of some 

 of its elements, fat is stored for the future needs of the organism. 

 A diminution of food, especially of fat and carbohydrates, is promptly 

 followed by an absorption of fat by 

 the blood-vessels and by its transfer- 

 ence to the tissues, where it is either 

 utilized for tissue construction or for 

 oxidation purposes. In the situations 

 in which adipose tissue is found it 

 seems, by its chemic and physical 

 properties, to assist in the prevention 

 of a too rapid radiation of heat from 

 the body, to give form and roundness, 

 and to diminish angularities, etc. 



Retiform and adenoid tissue are 

 also modifications of areolar tissue. 

 The meshes of the former contain but 

 little ground substance, its place being 

 taken by fluids; the meshes of the 

 latter contain large numbers of lymph 

 corpuscles. 



Fibrous Tissue. This variety of connective tissue is widely 

 distributed throughout the body. It constitutes almost entirely the 

 ligaments around the joints, the tendons of the muscles, the mem- 

 branes covering organs such as the heart, liver, nervous system, 

 bones, etc. All fibrous tissue, wherever found, can be resolved into 

 elementary bundles, which on microscopic examination are seen to 

 consist of delicate, wavy, transparent, homogeneous fibers, which 

 pursue an independent course, neither branching nor uniting with 

 adjoining fibers. (See Fig. 9.) A small amount of ground substance 

 serves to hold them together. Fibrous tissue is tough and inexten- 

 sible, and in consequence is admirably adapted to fulfil various 

 mechanical functions in the body. It is, however, quite pliant, bend- 

 ing easily in all directions. When boiled, fibrous tissue yields gelatin, 

 a derivative of collagen. 



FIG. 9. CONNECTIVE - TISSUE 

 BUNDLES OF VARIOUS 

 THICKNESSES OF THE IN- 



TERMUSCULAR CONNECTIVE 



TISSUE OF MAN. X 240. 



