22 



HAND-BOOK OF PHYSIOLOGY. 



When a small portion of a perfectly fresh serous membrane, as the 

 mesentery or omentum (Fig. 15), is immersed for a few minutes in a 

 quarter per cent, solution of this re-agent, washed with water and exposed 

 to the action of light, the silver oxide is precipitated along the bounda- 



Fio. 15. Part of the omentum of a cat, stained in silver nitrate, X 100. The tissue forms a "fenes- 

 trated membrane," that is to say, one which is studded with holes or windows. In the figure these 

 are of various shapes and sizes, leaving trabeculae, the basis of which is fibrous tissue. The trabecu- 

 Ise are of various sizes, and are covered with endothelial cells, the nuclei of which have been made 

 evident by staining with hasmatoxylin after the silver nitrate has outlined the cells by staining the 

 intercellular substance. (V. D. Harris.) 



ries of the cells, and the whole surface is found to be marked out with 

 exquisite delicacy, by fine dark lines, into a number of polygonal spaces 

 (endothelial cells) (Figs. 15 and 16). 



Endothelium lines, as before mentioned, all the serous cavities of the 



FIG. 16. Abdominal surface of centrum tendineum of diaphragm of rabbit, showing the general 

 polygonal shape of the endothelial cells; each is nucleated. (Klein.) x 300. 



body, including the anterior chamber of the eye, also the synovial mem- 

 branes of joints, and the interior of the heart and of all blood-vessels and 

 lymphatics. It forms also a delicate investing sheath for nerve-fibres 



