242 RETROGRADE SECT. XXIX. 2. 7. 



tinal canal : the punfta 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 noftriJs , but when the naf- 

 al duct is obitru&ed, and the hcrymal fack diftended with its 

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

 (punfta lacrymaiia) will readily difgorge the fluid they had pre- 

 vioufly abforbed, back into the eye. 



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

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

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

 of glands, in every refpedl (imilar to the fecretory vefTels of the 

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

 thefe capillary veflels have frequent anaftomofis into each other, 

 in which circumltance they are refernbled by the lafteals : and 

 like the mouths or beginnings of other glands, they are a fet 

 of abforbent veflels, which drink up the blood which is brought 

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

 for the circulation of the blood through the capillaries is proved 

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

 fhame, and in partial inflammations, their alion 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 diftrefies of the dying creature. Haller, 

 Elem. Phyfiol. 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 demonftration of the fluids in this difeaf- 

 ed condition of the animal, repafling through venous valves : 

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

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

 jefled to microfcopic obfervation, they would alfo in the difeaf- 

 ed ftate of the animal, be feen to repafs the valves, and the 

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

 promoted their progrefllon, 



Mr. Cooper relates fome curious inftances of difeafed valves 

 of the abforbent fyftem, and found on difleding 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 furfaces of the pancreas, and of the kidneys \ 



part 



