58 



cells become broken. In certain places there are cells which 

 surround the bundles and offer a great resistance to the pressure. 

 The bundles here swell up between bands of cells and leave 

 constrictions where the cells remain intact. 



In some pigmented parts of the body (skin, eye) the pro- 

 toplasm of the fixed connective-tissue cells contains brown, 

 black (melanin), or other colored granules. These are the so- 

 called pigment cells (Fig. 32). Pigment granules are insoluble 



FIG. 32. 



Pigment cell from the skin of a young salamander, x 200. 



in water, alcohol, ether, and dilute acids. They dissolve in 

 alkalies and lose their color in chlorine-water. They are a 

 product of the protoplasm formed from materials taken up from 

 the blood. Pigment cells often are found abundantly in the 

 skin of lower animals, where they are very large and stellate, 

 and have the power of moving themselves by means of processes. 

 These movements are supposed by some to be under the influ- 

 ence of the nervous system, and nerve-endings have been recog- 

 nized in the cells (Leydig, Ballowitz, Eberth, and Gunge). 



Fixed connective-tissue cells may also develop within their 

 protoplasm fine fat globules, which flow together to a large 

 droplet and give rise to the so-called fat cells or signet-ring cells 

 (Fig. 33). When a great many of these cells gather together, 

 they are spoken of as fatty tissue or fat (see below). 



(/?) Granular Cells : 



1. Plasma cells ; 



2. Mast cells of Ehrlich ; 



3. Clasmatocytes of Ranvier. 



