ABSORPTION. 



25 



against, the supposed connexion between the 

 two sets of vessels could not be demonstrated.* 

 In those experiments, where the thoracic duct 

 had been artificially obstructed, or in the cases 

 where the same thing had occurred as the 

 result of disease or malformation, they were 

 enabled to detect some supplementary vessels 

 or some indirect channel, by means of which 

 the chyle had been conveyed to the veins. 



With respect to the parts of the body, or 

 to the animals of an inferior order, which 

 were supposed not to be furnished with ab- 

 sorbent vessels, by prosecuting their examina- 

 tion with more care they gradually detected 

 the existence of these vessels in many cases 

 where they had not been previously known to 

 exist ; and they were discovered in so many 

 new situations that it became a fair inference 

 that every part of the body, and every animal 

 whose structure is generally analogous to that of 

 the mammalia, is provided with an appropriate 

 apparatus of absorption, although, from the 

 texture or the peculiar nature of the vessels, 

 it may be very difficult actually to demonstrate 

 their existence. In this train of investigation 

 the labours of William Hunter and Monro 

 were ably seconded by various anatomists, both 

 in this country and on the continent, among 

 whom we may select the distinguished names 

 of John Hunter, Hewson,f Cruikshank, and 

 Mascagni. 



* \Ve must, however, bear in mind that we have 

 the high authority of Meckel in favour of the com- 

 munication between the lymphatics and the veins ; 

 " Sur Resorption," Nouv. Mem. Acad. Berl. anil. 

 1770, p. 19 et seq. 



The researches of some of the most accurate 

 among the anatomists of the present day seem also 

 to show tl.at occasional communications exist be- 

 tween some of the lymphatics and the contiguous 

 veins' but this is a different kind of relation from that 

 which was contemplated by the older anatomists 

 between the sanguiterous and the absorbent systems. 

 This point is fully discussed by Fohmann, in his 

 late work, " Sur le commun. des vaiss. lymph, 

 avec les veins," vhere we have an account of his 

 own observations, as well as those of preceding 

 anatomists ; he conceives that the observations of 

 Lippi, of which an account is given in his " lllus- 

 trazioni fisiol.", are not correct : see also the 

 remarks of Antommarchi, Ann. Sc. Nat. t. xviii. 

 p. 108, 9. The observations of Fohmann have 

 been confirmed by Lauth, in his " Essai sur les 

 Vaisseaux Lymph." We may here refer to the 

 observations of Bleuland, which were made fifty 

 years ago, on what he styles the arteriohe lym- 

 phatics, by which a communication was supposed 

 to be maintained between the sanguiferous and 

 absorbent systems ; see his " Experim. Anat." 

 Panizza of Pavia also opposes the doctrine of 

 Lippi ; Osservazioni, c. 3 and 5. Mr. Abernethy, 

 in examining the vascular system of the whale, 

 discovered certain communications between the 

 sanguiferous and the lymphatic vessels ; but the 

 nature of the connexion is perhaps a little doubtful ; 

 Phil. Trans, for 1796, p. 27 et seq. For further 

 information on this subject, see a lecture on the 

 lymphatic system lately published by Dr. Graves. 

 Mr. Kiernan, in his elaborate researches into the 

 anatomy of the liver, gives it as his opinion that 

 the doctrine of Lippi has been " satisfactorily con- 

 futed " by Panizza ; Ph. Tr. 1833, p. 729. See 

 Elliotson's Physio! . p. 128,9 ; s. 1. also a paper in 

 Ann. Sc. Nat. t. 21. p. 252 et seq. 



t Phil. Trans, for 1768 and 1769; in these vo- 



The experiments of Hunter may deserve to 

 be particularly noticed, because they consisted 

 not merely in repeating and correcting those 

 of preceding anatomists ; but, in addition to 

 these, he entered upon a series of original 

 researches, which are highly characteristic of 

 that ingenuity and acuteness for which he was 

 so eminently distinguished. The experiments 

 essentially consisted in rilling portions of the 

 small intestines with a fluid, the sensible pro- 

 perties of which might be easily recognized, and 

 retaining it there so as to allow of its entering 

 into the veins of the mesentery, were they 

 capable of absorbing it ; the result, however, 

 is stated to have been that in no instance could 

 the fluid be detected in these veins. These 

 experiments appeared to have been so carefully 

 conducted, and so frequently repeated, as to 

 have impressed the minds of anatomists and 

 physiologists with a conviction that the lacteals 

 were the only vessels which are concerned in 

 the absorption of the chyle ; and although it 

 was not possible to perform analogous experi- 

 ments on the lymphatics, yet it seemed a 

 natural inference, that we might extend to them 

 the conclusion which had been established with 

 respect to the lacteals.* 



In proof of lymphatic absorption various 

 facts were brought forward, which seemed 

 clearly to show that when extraneous or noxious 

 substances were introduced into the system, it 

 was done by the medium of the lymphatic vessels 

 rather than of the veins ; and it was thence 

 argued that, as these vessels perform the func- 

 tion of absorption under certain circumstances, 

 and that we are not acquainted with any other 

 office which they serve in the system, we may 

 conclude that they are the sole agents in the 

 action of absorption. Although the argument, 

 as applied to the lymphatics, was far less 

 direct and conclusive than to the lacteals, yet 

 the analogy between the two organs appeared 

 so strong, and so many concurring circum- 

 stances appeared to favour the doctrine, that 

 it was very generally received, and may be 

 considered as having been the established 

 opinion at the conclusion of the last century .-{- 



This unanimity of opinion was, however, of 

 very short duration; for anatomists had scarcely 

 ceased to contend for the honour of the dis- 

 covery of the exclusive action of the lacteals 

 and the lymphatics in the function of absorp- 

 tion, when the doctrine itself was impugned 

 by physiologists of the first eminence, who 

 supported their views by a powerful train of 

 arguments, enforced by numerous experiments, 



lumes are contained his account of the lymphatics 

 of birds and fishes. 



* Med. Comment, c. 5 p. 42 . . 8 ; Cruikshank, 

 c. 5. p. 21. 



t See the judicious summary of opinions in 

 Mascagni, ps. i. sect. 2, 3 : and in Rullier, ubi 

 supra, p. 136 et seq. The doctrine of venous ab- 

 sorption was, however, still maintained by many 

 intelligent anatomists, especially by the high au- 

 thority of Meckel, De Fin. Ven. et Vas. Lymph. 

 1772 ; and of Walter, Sur la Resorption, ubi 

 supra. See particularly his general conclusion, 

 92 : he conceives that the veins are the only 

 agents in the absorption which is carried on at the 

 surface and from the cavities of the body. 



