2f>4 GENERAL ANATOMY. 



the continuity of the lymphatic vessels with the capillary arte- 

 ries finer than those which allow the passage of the coloured 

 globules of the blood. Haller, and most of the anatomists who 

 have lived since his time, admit no other origin to the lympha- 

 tic vessels than the tegumentary membranes. Some authors, 

 among whom is Mascagni, in admitting that lymphatic ves- 

 sels likewise arise from the parietes of blood vessels, thus in- 

 directly admit a communication, although they reject a direct 

 continuation. 



The inspection of living animals discloses nothing respect- 

 ing this communication. Injections sometimes pass, and even 

 frequently, but ordinarily colourless, from the arteries into 

 the lymphatic vessels; which may depend on the transuda- 

 tion in the cellular substance, and on the passage into the 

 lymphatics, which arise from it; or on the passage of the mi- 

 nute arteries into the lymphatic vessels of their parietes ad- 

 mitted by Mascagni, as well as upon a direct and immediate 

 communication, which consequently remains very doubtful. 



392. The serous capillary vessels which have been ad- 

 mitted beyond the capillary blood vessels, much more from 

 physiological considerations, than from positive anatomical 

 demonstration, is not the only hypothesis of this kind. Ab- 

 sorption and secretion being certain and evident facts, as al- 

 ready announced by the father of medicine,* many have been 

 the researches in order to find, by what passages substances 

 issue from the vascular system, and by what passages they 

 enter it. Without ever having seen them, they have been 

 described, the one under the name of exhalent or secretory 

 vessels, the other under that of absorbent or inhalent vessels. 



The exhalent vessels have been admitted by Haller, Hew- 

 son, Soernmering, Bichat, Chaussier, &c. as being very simple 

 vessels, appearing to be very minute and short productions of 

 the capillary arteries, and diffused in the tegumentary and 

 serous membranes, and the cellular tissue. 



Other anatomists, such as Mascagni, Prochaska, and Riche- 



* AA.oy, )V9crxf, 'c txTrvw, X.M s/V-mov oAcv TO rapx. Epedem. bib. vi. 

 sect. vi. 



