668 PHILOSOPHICAL TRANSACTIONS. [aNNO 176Q. 



The lymphatics are said to be the true, and only system of absorbing vessels. 

 I will suppose they are; though perhaps this opinion may yet admit of some 

 doubts: however, they certainly are the vessels that take up the watery latex from 

 most parts of the body, and return it back, to be again mixed with the blood. 

 This free absorption of the lymph is the great security against suffocation 

 injurious pressure, and an obstructed circulation in every part of the animal. 

 Many valuable discoveries have lately been made, of the existence of these 

 vessels in birds, fish, and amphibia. That most accurate and indefatigable 

 anatomist, Dr. Hunter, has written fully and explicitly on the lymphatics in the 

 human body; and yet, still it is to be wished, we knew more about them. 



We have not been able to see their origins in any one instance; we have not 

 traced them through the whole body, as we have done the blood-vessels. It is 

 reasonable to suppose they abound universally; but it is doubtful whether in 

 many parts they exist, or not; for the most eminent anatomists confess that, 

 there are many parts, in which hitherto they have ncjt been able to discover 

 them. 



It may not therefore be unentertaining to this learned society, who so 

 studiously promote every useful inquiry, not only to have a demonstrative proof 

 of the existence of lymphatics in a part of the human body where they have not 

 as yet been discovered; but also to have an opportunity of knowing that the 

 true origin of these vessels may easily be shown. As to their precise origin, it 

 has indeed been conjectured, and very reasonably, from experiments a posteriori. 

 It has been supposed they arise from all the surfaces and cavities of the body; 

 because thin fluids and subtle particles will be taken up from such cavities, or 

 surfaces, and will be readily enough conveyed into the blood: but then it has 

 never been shown, that they do arise from any one such surface or cavity. 



Commonly, the lymphatics are never filled from their beginnings, or little 

 orifices. When they have been injected, it has always been done by using some 

 violence; either by cutting into them, bursting, or tearing them asunder; so 

 that the injection rather gets in some how at the side, and not at the extremity 

 of the vessel. 



The lacteal vessels perhaps cannot, at least have never been, to my knowledge, 

 injected from the cavity of the intestine in the dead body. It is presumed that, 

 as the lymphatics are similar to these in other respects, their origins must be 

 also similar: that if the orifices of the lacteals are too fine to be discovered, the 

 mouths of the lymphatics are also too delicate to be traced out. But with 

 regard to the lymphatics of the human urinary bladder, it is certainly otherwise. 

 When the part is fresh and sound, we may, with a little trouble, blow into the 

 mouths of these vessels, small as they are; or introduce a fine bristle into them, 

 if we have but a steady hand and a good eye. I have frequently done both, in 



