242 RETROGRADE Sect. XXIX. 2. 



tinal canal : the pun£ta lacrymalia are abforbent mouths, that 

 take up the tears from the eye, when they have done their of- 

 fice there, and convey them into the noftrils ; but when the naf- 

 al duel is obftructed, and the lacrymal fack diftended with its- 

 fluid, on prefiiire with the finger the mouths of this gland 

 (pun da lacrymalia) will readily difgorge the fluid, they had pre- 

 vioully ablorbed, back into the eye. 



7. As the capillary vefTels receive blood from the arteries, 

 and fepanratlng the mucus, or perfpirable matter from it, convey 

 the remainder back by the veins ; thefe capillary vefTels are a fee 

 of glands, in every refpecr, fimilar to the decretory vefTels of the 

 liver, or other large congeries of glands. The beginnings of 

 thefe capillary vefTels have frequent anaflomofts into each other, 

 in winch circumftance they are refembled by the lacleals ; and 

 like the mouths or beginnings of other glands, they area fet 

 of abforbent vefTels, which drink iyp the blood which is brought 

 to them by the arteries, as the chyle is drunk up by the lacteals : 

 for the circulation of the blood through the capillaries is proved 

 to be independent of arterial impulfe ; fincc in the blufh of 

 fhamc, and in partial inflammations, their aclion is increafed, 

 without any increafe of the motion of the heart. 



8. Yet not only the mouths, or beginnings of thefe anaftomo- 

 fing capillaries are frequently feen by microfcopes, to regurgitate 

 fome particles of blood, during the ftruggles of the animal; but 

 retrograde motion of the blood, in the veins of thofe animals, 

 from the very heart to the extremity of the limbs, is obfervable, 

 by intervals, during the diftrefTes of the dying creature. Haller,- 

 Elem. Pbyfiol. t. i. p. 216. Now, as the veins have perhaps 

 all of them a valve fomewhere between their extremities and 

 the heart, here is ocular clem onftration of the fluids in thisdifeaf- 

 ed condition of the animal, repairing through venous valves: 

 and it is hence highly probable, from the Itricled analogy, that 

 if the courfe of the fluids, in the lymphatic veflels, could be fub- 

 jedted to microfcopic observation, they would alio, in the difeaf- 

 ed Mate of the animal, be feen* to repafs the valves, and the 

 mouths of thofe veflels, which had previoufly abforbed them, or 

 promoted their progrefTion. 



Mr. Cooper relates fome curious inftances of difcafed valves 

 of the abforbent fyftem, and found on difle&ing dogs, who had 

 died fome hours after he had put a ligature on the receptaculum 

 chyli, that in the cellular membrane of thofe dogs which had 

 their ftomachs full previous to the application of the ligature, 

 much chyle was effufed on many of the vifcera, and into the 

 cellular membrane connecting the laminae of the mefentery, 

 and on the anterior furfacefl of the pancreas, and of the kidneys ; 



part 



