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TEXT-BOOK OF PHYSIOLOGY. 



peritoneal, pericardial, etc., are also to be regarded as lymph-spaces. The 

 surfaces of these cavities, however, are covered with a layer of endothelial 

 cells with sinuous margins. At intervals between these cells are to be found 

 small free openings which have received the name of stomata. 



The lymph-capillaries in which the lymph-vessels proper take their 

 origin are arranged in the form of plexuses of quite irregular shape. In 

 most situations they are intimately interwoven with the blood-vessels, from 

 which they can be readily distinguished by their larger caliber and irregular 

 expansions. The wall of the lymph-capillary is formed by a single layer of 

 endothelial cells with characteristic sinuous outlines. These capillaries anas- 

 tomose very freely one with 

 another and communicate, on 

 the one hand, with the lymph- 

 spaces and on the other with 

 the lymph-vessels proper. It 

 was formerly believed that the 

 communication of the lymph- 

 capillary with the tissue space 

 was a direct one, the lymph 

 flowing from the latter into the 

 former through an open passage- 

 way. Recent investigation 

 would indicate that this histo- 

 logic arrangement does not exist 

 but that on the contrary the 

 lymph-capillaries are closed ves- 

 sels and that the tissue space and 

 the interior of the lymph-capil- 

 lary are separated one from the 

 other by a thin partition of endo- 

 thelial cells. As the shape, size, 

 etc., of both lymph- spaces and 

 capillaries are determined largely 

 by the nature of the tissue in 

 which they are found, it is not always possible to separate one from the 

 other. Their function, however, may be regarded as similar: viz., the 

 reception and collection of the excess of lymph which has transuded through 

 the walls of the blood-vessels and its transmission onward into the regular 

 lymph-vessels. 



The blood-capillaries not only permit of a transudation of the liquid 

 nutritive material from the blood through their delicate walls, but are also 

 engaged, if not in the resorption of a portion of this transudate, at least in the 

 absorption of waste products resulting from tissue metabolism. 



Lymph- vessels. The lymph-vessels constitute a system of minute, 

 delicate, transparent vessels found in nearly all the organs and tissues of the 

 body, and take their origin from the lymph-capillaries and spaces above 

 described (Figs. 87 and 88.) From their origin they gradually converge 

 toward the trunk of the body, and finally empty into the thoracic duct. In 

 their course they anastomose very freely with adjoining vessels. The 



FIG. 86. ORIGIN OF LYMPH-VESSELS FROM THE 

 CENTRAL TENDON OF THE DIAPHRAGM STAINED 

 WITH NITRATE OF SILVER, s. The lymph-spaces 

 and lymph-canals, communicating at x with the 

 lymphatics, a. Origin of the lymphatics by the 

 confluence of several juice canals. B. Capillary 

 blood-vessels. (Landois and Stirling.} 



