GLAND. 



of the lacrvmal gland. The prcfciicc of food in the mouth 

 excites the ialivnvy organs ; iind the a£l of faekling or milk- 

 ing jirodiicesa fecrctiun of milk, &c. &c. 



The fame powers hy which fecretion is effected accom- 

 pliOi the paffage of the fluid, when produced, tlirough its 

 excretory tubes ; it is the infenilble organic contraftility by 

 whicii this i; effefted. Experiments on the duifls of glands 

 in living animals, (hew that they are not affcfted by cliemi- 

 cal or mechanical irritation, and iience many have concluded 

 that they poflefs no power of contrac\ion ; but the pheno- 

 mena render it nccefiary to allow them fuch a property, 

 which may exifl in parts, although the trials juft mentioned 

 (hould not render it obvious. External prelTures and ex- 

 traneous influence of otlier kinds have been refortcd to, in 

 order to account for the expulfion of the fluids contained 

 in excretory tubes, on the idea that thefe canals poffefred no 

 contraftile powers in themfelves. Such explanations are 

 tjuite gratuitous affumptions in all cafes ; and in many 

 jnftances are tot.ally and manifeftly inadequate, bccaufe the 

 ergan is expofed to no agency of the kind. 



The fecreted fluid in fome initances is not conveyed imme- 

 diately to the point of its ultimate dcftination ; but is either 

 retained in the excretory tubes, or kept in particular refer- 

 voirs ; and it has been fuppofcd that various changes take 

 place in its nature and properties under thefe circumllances. 

 " Frequentiffime," fays Haller, "hoc mechanifmo natura 

 ulitur, ut humorem fecretum retineat, perficiat, infpiffet, ad 

 deftinatos ufus contempcret, legitiraa occaiione eff"undat." 

 Elem. Phyfiol. t. ii. p. 445. The urinary and gall-blad- 

 ders are the moll remarkable initances of tliis deicription : 

 we ma" mention alfo the veAcul.e feminales, and the mucous 

 dufts of the urethra and female organs of generation. That 

 the fecreted fluids in thefe, and in feveral other inftanees, are 

 coufiderably altered after the time of their firil produftion, 

 cannot admit of a doubt, as mere infpeftion is iufficient to 

 prove it ; the particular changes produced in each cafe will 

 be confidered in the account of the various organs The 

 opinions entertained concerning the general effe6ts of theie 

 refervoirs, are, that the fluids are inlpiffated by an abforp- 

 tion of thefe aqueous parts, that tliey are depurated, orrtn- 

 dered more perfeft, and varionfly mixed together : it is 

 added, that tlieir retention in the lieat of the living animal 

 body in many inflances renders them acrimonious, and tliat 

 this change, in many cafes, as in the bile and femen, promotes 

 the views of nature. Thefe notions are not very confident 

 with each otlier, nor very clear in themfelves : the latter 

 fuupofition, concerning tiie acrimonious tendency of the 

 fluids, is fountied on the obfervation of the changes occurring 

 out of the body, and is not at all warranted by obfervation 

 of the living fubjeft, in which chemical alterations are rc- 

 lided by thv? vital powers. 



We have every reafon to fuppofe that much of tlie fecreted 

 fluids is taken up and carried into the circulation by the ab- 

 forbents ; but our knowledge does not enable us to deter- 

 mine tlie exaft extent or nat-ure of the modification, which 

 tlie funftion of f_crction undergoes from this caufc. The 

 experiments of Bichat prove tliat the various animal pro- 

 dudls, even thofe which we fiiculd at Hrll have regarded as 

 the m.oil Boxious, may be introduced into the vcncuE fyflem 

 witho\it eifential injury to the animal ; fo that the blood 

 may be deemed a common fluid, receiving' and retaining 

 various principles, which may vary according to circum- 

 ftances. " I injecKd," fays Bicliat, " into the jugular veins 

 of feveral dogs, cyftic bile taken from other dogs opened at 

 ttkc fame time." Dhring the firll days they appeared v,-eary, 

 did not eat, v/cre very thirfty, had a dull look about the 



3 



eyes, and were conilantly lying down ; in a little time, how- 

 ever, they gradually recovered their original vigour. I have 

 fince employed human bile in limilar experiments ; the re- 

 fults were the fame, except that hiccough and vomiting 

 took place foon after the experiment. In one inllance tlie 

 animal died three hours after the injection ; here I h?d ufed 

 bile of an extremely deep black colour, like tiiick ink, 

 fuch as is occafionally feen in the gall-bladder, and ieems to 

 form an eflential part of the black vomitings obfervrd in 

 certain cafes. When iimilar trials were made with faliva, 

 the confequent languor was lefs fenfibie. I then tried mucus 

 of the nofe fufpended in water. Lallly urine itfelf, not of 

 the a([iieous kind, but that of coftion, was employed ; the 

 confequent ilhiefs was more fevere, but one animal only died, 

 and I fufpect that this fatal event happened from the un- 

 guarded introdudlion of a little air at the tin'.e of the experi- 

 ment.'' Anatomic Genvrale, t. 4. p. 587. He obferves 

 afterwards that the injection of any anin.al fluids into the 

 carotid artery is immediately fatal, from the cff^cdls produced 

 on the brain : but they may be thrown with impunity into 

 other parts of the arterial fyltcm, as, for inftance, into the 

 crural artery. 



S\mpallAes r,f the ghmdular f\Jl in — Tliefe may be divided 

 into the paffive and aftive. The glandular tifiuc is very 

 readily influenced by various excitements, either in tlie na- 

 tural Hate, or in difeafes, which conftitute its paffive fym- 

 pathies. The cafes in which the excitation of other organs 

 augments glandular aftion, arc particularly obfervable in the 

 mucous fyltcm. Moll of the excretory dufts open on fur- 

 faces of this nature ; and examples of the obfervation occur 

 in the flow of faliva determined by the prefence of food in 

 the mouth ; in that of urine produced bv catheters retained 

 in the bladder ; in the feminal excretion produced by irrita- 

 tion of the glans ; the flow of tears from irritation of the 

 conjunctiva or pituitary membrane ; and in that of bile 

 during the paifage of the food into the fmall intellinc. 



The glandular fyilcm frequently exhibits paflive fympathies 

 in dileaie ; the organic properties arc brought into a£tioi# 

 under thefe circumilances, the animal fenfibility being very 

 fcKlom de\ eloped fo as to produce pain. The innnmerable 

 varieties in the quantity or quality of fluids feparated by the 

 glandu under circuiviftancts of difeafe arife principally from 

 fympathetit influence. Thus the falivary apparatus n-.oittens 

 ttie mouth, or leaves it dry ; fills it witii a vifcid or a thin 

 fluid, S;c. The mucous organs cover the tongue with mat- 

 ters of nioft varying confiflcnce, thickncfs, and colour ; and 

 this occurs frcm fynipathy with various ihites of the ftomach. 

 The liver, kidney, and pancreas are influenced in very nu- 

 merous ways ; wherever any organ in the animal economy is 

 affeiled, thefe arc deranged ; their fecrction is increafed, di- 

 minilhed, or altered, and frequently even inflammation and 

 fuppuration fupcrvcne. Thcafililions of the liver from in- 

 juries of the head are well known ; and the lacrvmal fecrc- 

 tion is varioudy modified in inflam.matory and malignant fe- 

 vers, fo as to produce variouo appearances of the eyes. 

 Weeping in various mental affetlions is another example of 

 fympathetic influence. The tefticles and prollate exhibit 

 fewer inftanees of fuch fympathies, probably becaufe their 

 funciions are fo much more ifolated. Tlie relations which 

 conneft the breafts and uterus are remarkable, and frequent- 

 ly obferved. In the fequel of confiderable acute diieafes, 

 particularly fevers, the action of the glands is often confi- 

 derably affected, and copious evacuations, called critical, the ■ 

 nature of which is not yet clearly explained, take 

 place. 



The aftive fympatliies are lefs frequent than thofe of the 



pre ce- 



