THE MICROSCOPE IN ANIMAL HISTOLOGY. 195 



the tunics of the body, afford examples of the fibrillar 

 connective tissue. 



Fatty Tissue. The loose connective tissue contains in 

 various parts great numbers of cells filled with fat. Their 

 form is round, or oval, and are often divided into groups, 

 or lobules, by trabeculse. (Plate XIX, Fig. 148.) Each 

 lobule has its own system of bloodvessels, which divide 

 into such numerous capillaries that the smaller groups, 

 and even individual fat-cells, are surrounded by vascular 

 loops. Sometimes the contents of the cells appear in 

 needle-shaped crystals, often collected in a brush-like form. 

 Fat-cells seem to be chiefly receptacles for the deposit of 

 superabundant oleaginous nutriment, and are analogous 

 to the starch-cells in vegetables. 



Cartilage. This is formed of cells in an originally homo- 

 geneous intercellular substance. The only difference be- 

 tween what was formerly distinguished as cartilage and 

 fibro-cartilas:e is that the matrix or intercellular substance 



O 



of the latter is fibrous. 



The cells, or cartilage-corpuscles, are nucleated, and lie 

 in cavities of various sizes and form in the matrix (Plate 

 XX, Fig. 149). Two nuclei often appear in one cell. It 

 is yet a question whether the capsule and matrix are the 

 secretion of the cells which has become solid, or a part of 

 the body of the cell which has undergone metamorphosis. 



The multiplication of cartilage-cells is endogenous. By 

 segmentation, two, four, or a whole generation of daughter- 

 cells, so called, may lie in the interior of a capsule. In this 

 way growing cartilage may acquire a great number of 

 elements. 



In the ear of the mouse, etc., we observe a form of car- 

 tilage which is wholly cellular, and possesses no matrix 

 (Plate XX, Fig. 150). 



Bone, or osseous tissue, is formed secondarily from meta- 

 morphosed descendants of cartilage or connective-tissue 

 cells, and is the most complex structure of this group. It 



