CHAPTER I. 



THE ENDOTHELIUM OF TEE FREE SURFACE OF THE SEROUS MEMBRANES. 



A GENERAL description of the endothelium of the free surface of the 

 serous membranes is hardly necessary after those given by Reckling- 

 hausen, Auerbach, Ludwig and Schweigger-Seidel, Dybkovsky and 

 others. 



Some points only will be treated of in this chapter, which have 

 not yet been sufficiently appreciated. 



The endothelium of the free surface is in the normal condition not 

 everywhere a layer of flattened more or less hyaline cell-plates, but 

 possesses in many places a different character, which may be described 

 as follows : the individual cells are polyhedral, club-shaped, or even 

 short columnar, their substance is distinctly granular, even in the 

 fresh condition, their nucleus is for the most part, like that of the 

 ordinary endothelial plates, ovodi, sometimes spherical, clear, sharp- 

 outlined, with a large shining nucleolus. In many cells, however, the 

 nucleus is marked by a constriction, or is even perfectly divided into 

 two. 



A portion of the fenestrated part of the fresh omentum of a full- 

 grown guinea-pig, cat, dog or monkey, mounted in an indifferent fluid, 

 such as one-half per cent, saline solution, peritoneal fluid, etc., or after 

 having been stained in one-quarter or one-half per cent, solution of 

 nitrate of silver and mounted in glycerine, shows often enough on the 

 surface of the thin trabeculse small groups of club-shaped or poly- 

 hedral granular cells, projecting from the surface of the trabeculae like 

 buds. If one follows a large trabecula, which contains either large 

 blood vessels only, or besides those, also tracts of fat-tissue, one can 

 always find smaller or larger arese, generally on one surface only, the 



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