GLAND. 



liitlierto derived from this fource in unfolding tlie myllery. 

 Tint tliL- changes, by whicli the new products conllitiiting tlie 

 animal fluids are produced from tlie blood are purely ciiemical, 

 cannot be doubted, but we are equally in the dark as to the 

 circu:nllances whicli determine or modify theR- alterations. 



do not ceafe to aft where that org^n is paralyfcd. Aft^rr 

 cutlin;^ tlie nerve of the eightli pair on one fide in a dog, the 

 air-veliels are equally full of mucus on that fide. In the 

 coiivulfed (late of fuch jiarls as polTefg glands, where the 

 nerves of tliefe organs nuifl confcqucntly be unufually e\- 



by accurate chemical inveiligations We may apply generally 

 the obfervation of Dr. Tiiomlon concerning the kidnies : 

 " the changes operated on tli? b!ood in the kidnies are at 

 prefent altogether unknown ; but they muil be important, 

 provided the molhod of air.dyiing animal fubilances vfas fo 

 far perfedted as to admit of accurate conclufions, confider- 

 able light miglit be thrown upon tliis fubject, by analyfing 



We cannot doubt indeed that t!ie whole effentially depends on cited, there is no augmentation of the fecretion " Ana- 

 a vital power of which chemillry can neither deleft the toniie Generale, torn. 4. p. 604. We may obfervc further, 

 nature, nor appretiate the force. If, however, we cannot be that wlien the influence of the brain on the organs of the 

 very fanguine in expecting from this fcience a developjment animal life is completely fufpended in apoplexy or coir., 

 of the immediate agent by which fecretion is eA'cfted, much preifion, where fenfation'and voluntary motion are lofl, the 

 light may, probably, be thrown on fome parts of the fiibjedt fecretions continue undiUurbed. On the other fide wc'inar 



adduce i)\imerous phenomena, which can be accounted for 

 only through the agency of the nervous fyilem. Lender tin's 

 head we may mention the How of falivaon the fight of food, 

 the increafcd lacrymal fecretion produced bv various 

 affedions of the mind, the fupprefled difcharge ' frMn the 

 ikin from the fame caufe. The urinary fecretion is often 

 „ _ . . . . . „ luddeiily aflefted in hypochondriacal perfons ; dillrelTing 



with care a portion of bload from the emulgent artery and news will occaiion it to be fecreted in great abundance, and of 

 vein feparateiy, and afcertainiiig precifely in what particulars a very pale colour ; and many remarkable inllances liave 

 they differ from each other." Syftem of Chemillry, vol. 5. been recorded, where the biliary fecretion has been decidedly 

 p. 749. Fourcroy, too, in conhdering how far fecretion and fuddenly afltfted by mental emotions. It has beea 

 admits of explanation on chemical principles, fpeaks rather alferted, but we know not on what authority, that jn cow, 

 of what may be done than of what has been cffecled in this after being milked by the fame individual for a lono- time, 

 way. "Hitherto chemillry can only furnifli fome general will give much lefs milk, if the operation be performed by a 

 ftatements on this fubjeil ; and, if we look to this fcience ftranger. Thefe and other analogous fadts have led manv 

 for an explanation oi tiie caules and produfts of the fecre- phyfiologifts to admit of a nervous influence in the affair of 

 tions, and for a demonllratioii of what partes in every kind iecretion ; the mode and degree of this aftion have bei-n va- 

 of fecretion in particular, we mull wait till the experiments rioufly ellimated. De Berger conceives that the tone of the 

 are much more numerous, the invelligations more exaft, and fecretory organs wa« kept up by the nervous fluid; Dc 

 the animal analyfes confiderably multiplied. We mufl; de- Natura Humana, p. 122. Quefnay referred the difierenees 

 termine the temperature, confidence, and nature of the cere- of the fecreted fluids to various degrees of fenfibility in the 

 brai blood, of that in the vena portanim, and in the renal fecretory veffels ; Eflais fur I'Econ. Anijn. t. 3. p. 4^7 



arteries, before we can underlland the mechanifm of the 

 fecretions performed in the brain, liver, and kidnies.'' Syll. 

 des Conn. Chimi. v. 10, p. 385. 



We fliould always bear in mind, in our attempts at che- 

 mical explanations of the animal func"Hons, that the effcdls 

 of the vital power are more particularly obfervable in coun- 

 teracting and preventing the exertion of thofe affinities, by 

 which dead animal matters are regidated ; and confequently, 

 that if fecretion be an example of chemical affinity, it is fo 

 modified by the vital powers, that we can have very little 

 hope of imitating it by experiments out of the body. 



In what manner, and to what extent, are the fecretions 

 influenced by the nerves ? The faft tliat gland* have a fup- 

 ply ot nerves, leads us to expeA ii priori that the effecfls of 

 their operation will be very obvious ; but the laws, which 

 regulate this matter, are hitherto by no means clearly afcer- 

 tained, and even the kind of influence is very obfcure. There 

 is a want of dirett evidence, from experiment, on this fub- 

 jeft. " I divided," fays Bichat, "the nerves of the 

 Vefticle in a dog : the gland inflamed and fuppurated ; but 

 the latter occurrence fhews that nervous influence is not ne- 

 ceifary for fecretion, lince fuppuration is accomplilhed in a 

 manner analogous to that of the latter fumilions. Pliyficiaus 

 know very well that paralyled limbs may inflame and fup- 

 purate. Ereftion and expullion of the femen may occur, 

 when the lower half of the body is paralyfcd, and when the 

 nerves of the proftate at leaft muil have entirely lofl their 

 influence. An example was related to me of a foldier, who 

 contracted a gonorrhaca in this ftate. In complete paialyiis 

 of the bladder, mucus is tlill fecreted in fufiicient abundance, 

 Tiie nollril of the aff"etted fide is as moiil as ufual in hemi- 

 plegia ; aqd an equal quantity of cerumen is produced in the 

 meatus auditorius of the fame fide. The glands of the uvula 

 VDt,. XVI 



De Bordeu afcribed great influence to the nerves on the fe- 

 creting arteries ; Recherches fur les Glandes, p. 352. Stahl 

 and his followers, who afcribed the power of guiding the 

 vital motions to the foul (anima), conceived that it go- 

 verned the buiinefs of fecretion alio ; and A. F. Hoffman 

 afcribes the difference of the fluids entirely to the anima, 

 which regulates the fecretory orifices by fphinilers and 

 valves, now clofing them to prevent the entrance of par- 

 tides heterogeneous to the fluid intended to be formed, and 

 now opening them for tlie entrance of the fuitable molecules u 

 Nov. Hypothef. Phyliolog. p. 13. After recounting thele 

 opinions, Haller obferves that thcv afcribe too great aa 

 influence to the nerves, and reminds his reader that fecre- 

 tions of various kinds arc performed in plants, without the 

 afllllance of nerves ; and that balfams, relins, gums, and 

 coloured milky fluid is formed from the common liquor taktn 

 in by the roots of the vegetable. On this fubjeci 

 we may obferve, with Bichat, that the exprcllion lur- 

 •uous irjlufiice has gciierallT been ufed by phyfiologifts in a 

 very indefinite manner. When tlie irritation, divilion, cr pa- 

 ralylis of a nerve fupplying a voluntary organ interrupt.s, or 

 entirely dellroys its fuiiclions, we can o'blerve and apprc- 

 tiate the influence of the nerves on Inch organs ; but, wih 

 what propriet)- can \ye employ the fame term to di. fignate ■ 

 the power, which the nerves mav pofl'ibly have over the fe- 

 cretory organs, when their divifionor paraly lis due> uut at all 

 diilurb the functions of the part : 



The fecretii>ns may be affeded bv the direi^ aclion of 

 external irritants, altliough mechanical or cluinical irritatiou 

 in the living body produces no fenfible motion or contraction 

 of the organ. Thus, any acid matter will augment the flow 

 of mucus from thofe lurfaces whjjh ficrete it ; and the 

 ilightell irritation of the conjundtirA iiicrcafeS the fcij-eti-ju 

 (^q «» 



