26 PRACTICAL HISTOLOGY. 



nitrate of silver just as in cartilage (p. 17) ; the silver blackens the intercellular parts and 

 leaves the spaces occupied by the cells clear. 



PREPARATION. Take several of the freshly exposed tendons of the tail of a rat. Wash 

 them with a camel-hair pencil dipped in distilled water. Do this several times to remove 

 the epithelium which covers their surface. Place the tendons in a half per cent, solution of 

 nitrate of silver for five minutes. Then wash them in water and mount a small piece of a 

 tendon so treated in glycerine ; and expose it to the light until it assumes a brownish colour. 



EXAMINATION (H). Observe the irregular spaces seen in a dark brown matrix. These 

 spaces communicate one with another by fine clear lines. The brown stained part indicates 

 the existence of an intercellular substance ; in the clear spaces lie the cells with their 

 processes. 



EPITHELIAL COVERING OF TENDONS. 



Each of the fine tendons is enveloped by a layer of squamous epithelium, which is easily 

 demonstrated by staining the tendons without previous pencilling with nitrate of silver as 

 directed above. Mount a tendon in glycerine, and expose it to light until it becomes brownish 

 in colour. 



EXAMINATION (H). The outlines of the polygonal epithelium are distinctly seen. These 

 indicate the existence of an epithelial investment of the tendon superficial to the fibres and 

 cells already described. 



MEMBRANOUS CONNECTIVE TISSUE. 



THE OMENTUM. 



A convenient form of this tissue is found in the omentum, which differs in its characters 

 in various animals, and also in young and in adult animals. In an adult cat the omentum 

 consists of bundles of connective tissue of various sizes, cemented to each other in the same 

 plane, so as to form a network. In the larger trabeculae blood-vessels and fat-cells are found. 

 Each bundle of fibres is completely invested by a layer of squamous epithelium or endothelium, 

 and the nuclei of these cells can readily be seen, on the surface or edges of the fibres when they 

 are stained. The trabeculas consist of fibrils which can be seen in the fresh tissue. In the 

 substance of the trabeculse and amongst the fibrils a few fusiform corpuscles the connective- 

 tissue corpuscles may be seen. They are relatively few in number, and so are the elastic 

 fibres. 



In a young growing rabbit the omentum is much less fenestrated, and forms a more 

 continuous sheet of connective tissue, covered on each surface with a layer of endothelial 

 squames. As the animal becomes older the membrane becomes more fenestrated. 



PREPARATION. Silver Nitrate. Remove the omentum from an adult cat and rabbit, 

 and also from a young rabbit just killed. Wash each in distilled water to remove the soluble 

 chlorides, and then place them in a quarter per cent, solution of nitrate of silver for five minutes, 

 and, after washing them thoroughly, expose them in alcohol to the light till they become brown. 

 Snip out a small piece of each with scissors, and float them from water on to slides in the usual 

 way (p. xxvi). Mount in Farrant's solution and cover, or similar preparations may be stained 

 with logwood, which stains the nuclei. 



