IO8 THE TISSUES. 



courses through the center of the fat lobule, breaking up into 

 capillaries which form a network around the fat cells. The capil- 

 laries unite to form several veins which are situated at the periphery 

 of the lobule. Where fat cells develop from connective-tissue 

 cells, even though these are present in considerable number this 

 typic arrangement of the blood-vessels is wanting. 



Microscopically, fat is easily recognized by its peculiar glistening 

 appearance (by direct light). It has a specific reaction to certain 

 reagents. It becomes black on treatment with osmic acid, and is 

 stained red by Sudan III and blue in cyanin. 



5. CARTILAGE. 



Cartilage is readily distinguished from other connective tissues 

 by its ground-substance or matrix, intercellular substance, 

 which yields chondrin on boiling. Three varieties are found in 

 higher vertebrates: (i) hyaline cartilage; (2) elastic cartilage; (3) 

 white fibro-cartilage or connective-tissue cartilage. 



The simplest type is hyaline cartilage, so named because of its 



Cartilage cell. :''Jj 



Fig. 76. Hyaline cartilage (costal cartilage of the ox). Alcohol preparation ; 

 X 300. The cells are seen inclosed in their capsules. In the figure a are represented 

 frequent but by no means characteristic radiate structures. 



homogeneous and transparent ground-substance, which, however, 

 in reality consists of fibrils and an interfibrillar substance, the two 

 having essentially the same refractive index. In this ground- 

 substance are found the cartilage cells, occupying spaces known as 

 lacunae. The spaces or lacuna:; are surrounded by a narrow zone 

 of ground-substance, which does not stain as does the ground- 



