PHYSIOLOGY. 



is stated on this subject in the article 

 ANATOMT. 



The admission of matter into the 

 orifices of the absorbing vessels has 

 been accounted for in various ways. 

 Some physiologists consider it as a case 

 of capillary attraction. But a little re- 

 flection is sufficient to shew that the 

 absorbents are not like capillary tubes 

 immersed in a fluid. Besides, were 

 such attraction the cause of absorp- 

 tion, that process should be carried on 

 with regularity. On the contrary, absorp- 

 tion is occasionally very deficient, when 

 abundance of fluids is presented to the 

 mouths of the vessels, as in oedema; and 

 in other cases, after being for a long time 

 inactive, it is suddenly exerted to a great 

 extent ; thus large abscesses have been 

 dispersed in one night. Others have en- 

 deavoured to discover some propelling 

 power which should protrude the matter 

 subject to absorption into the mouths of 

 the vessels. The pressure of the atmos- 

 phere on the suiface of the body has been 

 considered adequate to this effect, and 

 the deposition of new matter by the se- 

 cerning artery has been assigned as the 

 cause of the propulsion of the old parti- 

 $Ies into the orifice of the absorbent. On 

 this theory, secretion and absorption 

 should correspond more exactly than they 

 are known to do. Mr. J. Hunter acknow- 

 ledged that he was unable to account for 

 the effects product d, unless by attribut- 

 ing to the mouths of the absorbing ves- 

 sels powers similar to those which a ca- 

 terpillar exerts when feeding on a leaf. 



Some suppose that the absorbents can- 

 not take up any matter that is not fluid; 

 consequently, that animal solids must be 

 converted into fluids before they can be- 

 come fit subjects for absorption ; and that 

 probably some solvent fluid is secreted 

 for this purpose. The latter fact rests on 

 no direct proof, and the whole hypothe- 

 sis is very unlike the simplicity observa- 

 ble in other parts of the animal economy. 

 It seems better, in these difficult investi- 

 gations, to note facts, than to form theo- 

 ries ; and whoever contemplates the 

 things done in the animal body, will be 

 astonished at the power of the vessels, by 

 whose agency they must be effected ; a 

 whole bone may perish, as, for example, 

 that of the thigh, and may be increased 

 by a new one ; the vascular lining of the 

 new bone will altogether remove the 

 dead one. 



Besides the great and leading office of 

 the absorbents in conveying the chyle 

 into the venous system, their agency is 



discerned in various other parts of the 

 animal economy. The nearly transparent 

 fluid that lubricates the interstices of the 

 cellular substance, and the serous exha- 

 lation poured into circumscribed cavities, 

 are taken up by the lymphatics, which 

 must commence in all parts of the body 

 by open orifices. When the due balance 

 does not exist between the absorbing and 

 secreting vessels, the cellular substance 

 becomes loaded with fluid (anasurca), or 

 circumscribed cavities are rendered drop- 

 sical. Together with the lymph or fluid 

 which the absorbing vessels derive from 

 the sources just mentioned, they convey 

 from every part of the body the old con- 

 stituent materials of our organs, in pro- 

 portion as new particles are deposited by 

 the arteries ; and these different elements 

 are intimately mingled and combined in 

 their passage through the absorbent 

 glands, and the plexures of lymphatic 

 vessels. 



It has been a disputed point whether 

 absorption goes on from the surface of 

 the skin, while the cuticle is entire ; the 

 arguments on the affirmative sides are an 

 alleged increase of weight in the body 

 after a walk in damp weather ; the abun- 

 dant secretion of urine after remaining 

 for some time in a bath ; the evident swell- 

 ing of the inguinal glands after a long 

 immersion of the lower extremities in 

 warm water ; the effects of mercury ad- 

 ministered by friction, fumigation, &c. It 

 has been stated in opposition, that oil of 

 turpentine has not been absorbed after 

 long immersion of the arm ; that solutions 

 of medicated substances have not been 

 taken up under similar circumstances, 

 &c. We think it is sufficiently proved, 

 that absorption from the surface does take 

 place in the human body, but whether 

 this extends, as a modern physiologist has 

 stated, to gaseous bodies, cannot yet be 

 decided. 



It appears probable that the internal 

 surface of the bronchi and pulmonary ve- 

 sicles is an absorbing surface. For when 

 a person breathes air loaded with the va- 

 pour of turpentine, that substance very 

 speedily shews itself in the urine, al- 

 though the skin will not take it up. If 

 the body really increase in weight in 

 damp air, it might be accounted for by 

 means of pulmonary absorption. It must 

 probably be rather in this way, or by the 

 skin, that contagious matters affect the 

 constitution. 



The absorbents are concerned in pro- 

 ducing changes in the different secreted 

 fluids : they remove the aqueous portions 



