CHAPTER VIII. 



THE BLOODVESSELS, 

 BY C. J. EBEBTH, 



PROFESSOR OP PATHOLOGICAL ANATOMY IN ZURICH. 



IN adult vertebrate animals the essential constituent of the 

 bloodvessels is a tubular system formed of a single layer of flat 

 cells, or of a delicate nucleated membrane, termed the endothelial 

 tube by His,* the perithelial tube by Auerbach,f and the cell 

 membrane by Remak.J This tube is the least variable part of 

 the vascular walls, and is present alike in the finest bloodvessels, 

 in the largest trunks, and in the dilated portions of the vascular 

 system the heart and the several sinuses however much the 

 other constituents of the vascular wall may vary. In a few 

 organs, however, as in the spleen of Mammals, in the pulmonary 

 organs of the Cephalophora,and in the gills of Crustacea, the pas- 

 sages through which the blood courses appear to be destitute of 

 a proper wall. The capillaries and smaller veins are formed of 

 this tube alone, the elementary constituents of which are deli- 

 cate, flattened, more or less fusiform, or polygonal cells, com- 

 posed of a nucleus with surrounding protoplasm, and arranged 

 for the most part parallel to the long axis of the vessels. 



In the heart and arteries, and in most of the veins, this cell 

 tube is invested by connective tissue and by elastic and 



* Die Haute und Hohlen des Korpers. Basel, 1866. 



f Virchow's Archiv, Band xxxiii., 1865. 



J Miiller's Archiv, 1850. 



Bidder, in his Beitrage zur Gynakologie und Geburtskunde, v. Hoist,- 

 1867, has incorrectly denied the presence of an endothelium in the margi- 

 nal veins of the placenta. See Eberth, Virchow's Archiv, Band xliii., p. 

 136, 1868. 



