34 ABSORPTION, 



removal of a part by pressure. If a muscle, or the subject, some physiologists have supposed 



even a solid bone be exposed to constant pres- that the glands are proper secreting organs, 



sure, by which its nutritive arteries are ob- which are destined for the purpose of preparing 



structed, it will be gradually diminished in a peculiar substance that is mixed with the 



bulk, and at length completely abstracted, chyle and the lymph, or that they merely serve 



And this is frequently effected by the action of the mechanical purpose of mixing together more 



a body much softer than the substance which completely the constituents of the fluid that is 



is removed, as, for instance, we observe a bone contained in the vessels, and thus produce 



to be absorbed by the pulsation of a blood- some change in its nature or consistence.* 



vessel, or the growth of a fleshy tumour.* There do not appear to be any arguments, either 



But although we may venture to aftirm that anatomical or physiological, by which this point 



this moulding of the body, or rather of its in- can be decided ; but we may remark, that 



dividual parts, is effected by the lymphatics, while the number and mode of distribution of 



either alone or in conjunction with the veins, these glands in the mammalia would seem to 



there is considerable difficulty in forming a point them out as performing some important 



distinct conception of the mode in which they office in the animal economy, their rarity in 



operate. The operation cannot, strictly speak- birds and fishes proves that they are not essen- 



ing, be mechanical, nor have we any evidence tial to the existence of most of the functions of 



of the existence of a chemical solvent, by animal life, nor have we any mode of explaining 



which the parts may be reduced to a liquid the cause why they should be more necessary 



state, so as to fit them for entering into the to the mammalia than to the other classes, 



mouths of the vessels. We may conceive of which in many of their functions so nearly re- 



the source of supply being cut off by pressure semble them. 



or in other ways, but still we are at a loss to It only remains for us to offer a few remarks 



account for the mode in which the solids are on the connexion between the function of ab- 



either dissolved or broken down, so as to adapt sorption, and the other vital actions of the 



them to the process of absorption. There is, system, especially with the two leading princi- 



however, one principal or general fact in the pies of contractility and sensibility. We have 



animal economy, which will probably some- already had occasion to remark on the con- 



what assist us in our inquiry, viz. that it appears nexion of absorption with muscular contracti- 



to be essential to the well-being, or even to the lity, and although it may be difficult, or even 



existence of the corporeal frame, that all the impossible, to demonstrate the muscular fibres, 



materials of which it is composed should un- or to exhibit any apparatus of this description, 



dergo a constant change. It appears that these by which the action of the vessels can be ac- 



materials, after a certain length of time, expe- counted for, still we have strong reason for 



rience some alteration in their nature, by which supposing that the absorbents possess this 



they are rendered unfit for the further perform- power, and that it is the main cause by which 



ance of their functions as constituents of the their contents are propelled, 



living body. They are therefore removed and With respect to the relation which subsists 



are replaced by fresh matter, this interchange between the nervous and the absorbent systems, 



being brought about in the gradual manner we are induced to suppose, both from anato- 



which was described above. JNow this process mical and from physiological considerations, 



implies a constant decomposition of the parts that it is merely of an indirect nature. From 



of the body, and as this decomposition is the researches of the anatomists, we learn that 



effected particle by particle, it may not be un- there are few nerves sent to the absorbent vessels 



reasonable to conjecture, that each particle, or glands, and that even these seem rather to 



when it ceases to form an integral part of an pass by them, in order to be transmitted to 



organ, is left in a state proper for being taken some other organs, than to be ultimately des- 



up by the absorbents. But independent of any lined for the use of the absorbent system. The 



hypothetical views of this description, we may action of the mouths of the lacteals, or the 



assume it as a probable conclusion, that the power by which they are enabled to take up 



configuration and moulding of the body is the the substances that are afterwards transmitted 



specific and appropriate office of the lymphatics, along them, is involved in much obscurity, as 



while its nutrition is effected more immediately is likewise the case with the power which these 



by the lacteals. vessels seem to possess of changing the nature 



With respect to the lymphatic glands we of their contents. Both of these have been re- 

 have seen above that their structure is involved ferred to the nervous influence, but this has 

 in considerable obscurity, and we may remark, been done in that loose and general way, which 

 that their use is at least equally obscure. Among 



other opinions that have been entertained on 



* On this subject we may refer to Haller, El. 

 Phys. ii. 3. 25; Blumenbach, Inst. Phys. . 425, 



* For the absorption of the solids, see Monro on 442; Richeranrl, Elem. p. 153; Mascagni, ps. i. 



the Brain, c. 5; also Blumenbach, . 436; and sect. 5. p. 33 ; Magendie, Elem. t. ii. p. 166, 201 ; 



Bell's Anat. vol. iv. p. 311, 2. Ribes, who is a Chaussier et Adelon, ubi supra, p. 278. Rullier, 



zealous defender of the doctrine of venous absorp- art. " Inhalation," in Diet. Sc. Med. ; Meckel, 



tion, remarks that the absorption of the bones must Manuel, sect. 6. ch. i. ; Adelon, art. " Lymphatique 



be effected by the veins, because they are not fur- (Physiologic)," Diet, de Med. t. xiii, also art. 



nished with lymphatics ; Mem. Soc. d'Emulation, " Chyliferes," ibid. t. v. p. 239; Desgenettes, 



t. viii. p. 621. Journ. Med. t. xc. p. 322, et seq. 



