i60 



ON THE PROCESSES OF 



on account of their fineness, are called capillary ; and the absorbents, or 

 that set of vessels whose office it is to imbibe or drink up the waste and 

 exhausted materials, are as evidently distinct and attenuate tubes, pro- 

 gressively uniting, and ultimately emptying themselves into the venous 

 system, the common trunk in which they concentre, and in which also 

 concentre the lacteals of the ahmentary canal, named the thoracic duct, 

 being a tough membranous channel situate upon the interior part of the 

 spine, of about the diameter of a crow-quill in man, and running in a ser- 

 pentine direction through the diaphragm or midriff to an angle formed by 

 an union of the jugular and subclavian veins, into which it opens, and where 

 of course it terminates, leaving the waste and the new food, now inti- 

 mately intermixed, to be still farther elaborated and refkted for use by those 

 subsequent and specific operations of the heart and the lungs which we 

 have already described.* 



The simplest action, perhaps, that is evinced by the mouths of the secreto- 

 ry or secernent vessels, consists in separating and throwing forth a fine lymph 

 from the surface of all membranes and organs whatever, for the purpose 

 of lubricating them, as we grease the axle-tree of our carriage wheels ; 

 and thus preventing one membrane or organ from being injured by the 

 friction of another. Of this every one who has been present on the cut- 

 ting up of slaughtered oxen must have seen an abundant and striking in- 

 stance, in the vapour that ascends from every part of the warm carcass, 

 which vapour, when condensed by cold or any other cause, is found to 

 be little more than the serum or watery part of the blood. And one of 

 the simplest actions evinced by the mouths of the absorbent vessels, con- 

 sists in their drinking up, as with a sponge, this attenuate or lymphatic 

 fluid, when it has answered its purpose, so as to make room for a fresh 

 and perpetual eff'usion ; whence these vessels are often called lymphatic, 

 as well as absorbtnt, in consequence of their being so frequently found 

 loaded with this fine and colourless material. 



And here, perhaps, the first remark that must occur to every one is tbe 

 necessity there seems to exist, that these correspondent systems of vessels 

 should maintain the nicest harmony or balance in their respective func- 

 tions ; since, if the one operate either with a less or a larger power than 

 the other, disease must inevitably follow ; the nature of the malady being 

 determined by the nature ofA.\}e cause that produces it. 



We have all of us heard, and, most of us have seen instances of the 

 disorder called dropsy ; and many of us have surveyed it both in a local 

 and a general form, as dropsy of the head, dropsy of the chest, dropsy of 

 the abdomen, and dropsy of the cellular membrane or system at large. 

 This disease may take place from two causes ; as, for example, from a 

 too great excitement of the secernent system, or a too little excitement of 

 the absorbent, [f, f om a morbid irritability in the secernent vessels of 

 any one of the cavities I have just adverted to, an undue proportion of 



* This double action by a double set of vessels was little, if at all, known to the ancients, 

 who referred the economy of both secretion and absorption to the powers of peculiar arteries 

 and veins ; and hence, the porosity of these vessels was a doctrine in common belief, till the 

 time of He wson, Hunter, and Cruickshank. M. Magendie and M. Flaudrin, of Paris, have of 

 late been very active in establishing a view of the subject in many respects not essentially dif- 

 ferent from that of the old school, and in teaching that the only general absorbents are the 

 veins ; that the lacteals absorb food, but nothing else ; and that the lymphatics have no absorbent 

 power whatever. Their experiments are plausible and striking, but by no means decisive 

 enough to subvert the system explained above. The argument on both sides may be found m 

 the author',? Study of Medicine, Vol. v. p. 278, edit, 2d. 1825, 



