GLAND. 



gans. The mucous fluids, wliich appear to difTer more 

 confidcrably from the materials in the blood, are generally 

 feparated by particular glands, which are called crypts or 

 folhcles, contained in tlie fiibilance of the membranes or 

 vifcera. But it feems probable, that tlisfe alfo may be 

 feparated from the vafcular ramifications or a fimple mem- 

 branous tiffue without any exprefs glandular llrudlure, as 

 in the cafe of fevoral mucous membranes. It remains there- 

 fore for us at prefent to explain, in a general way, the 

 anatomical ftruCtiire of the various glands, by which the 

 other animal fluids are fecreted. 



The glandular differs from molt other fyflems, in the 

 animal economy, in this circumftance, that its pecuhar tiffue 

 is not exatlly identical in all the organs belonging to it. 

 Tlie fibres of any voluntary mufcle u'ould fcrve equally 

 well to compofe any other of the fame kind. Tendinous 

 fibres, cartilaginous and bony ftrndlnres, are the fame every 

 where. The fubftance of the hver, on the contrary, is 

 widely different from that of the kidney ; which again is 

 very diftinft in its charader from that of the falivary glands. 

 The glandular fyltem, therefore, is marked in its various 

 parts with very few general attributes, which alfo fuffer 

 many exceptions. 



Situation, farms, Jivi/ion, l^c. of the glandular fyflem 



Glands have two different fituations in the body. Some 

 are fubcutaneons, as the breads and falivary glands ; others 

 deeply feated, as the liver, kidnies, pancreas, and moll of 

 the mucous glands, and confequently, not expoled to the 

 aftion of the external bodies. Many of them occupy fitua- 

 tions where there is much motion, as the fahvary glands near 

 the jaw, the mucous in clofe contadl with a plane of mufcular 

 fibres, the liver in the vicinity of the diaphragm, &c. Thefe 

 fafts have led to the fuppofition that the neighbouring 

 motion, extraneous to their funftions, determined the ex- 

 cretion of the fecreted fluids. But, in the firft place, the 

 palatine glands, the pancreas, the telticles, and even the kid- 

 nies, are fo fituated, as to be out of the way of fuch external 

 alTiftance. And we obferve, further, that mucus is fecreted 

 as abundantly by the pituitary membrane, as in any other 

 part, although there is no mufcular plane here ; that the 

 lining of the bladder produces an equally copious fupply, 

 when the vifcus is paralytic ; and that various caufes aug- 

 ment the fecretions, without any conneftion with the circum- 

 ilance firft alluded to, as fialagogue medicines, or the fight of 

 food in the cafe of falivary glands. We cannot doubt, 

 therefore, as Bordeu has obferved, that this mechanical 

 caufe has nothing to do with the matter, and that the effen- 

 tial caufe of all excretion confifts in a peculiar vital aftion. 



Some glands are lingle, as the liver and pancreas ; 

 others are arranged in pairs, as the kidnies, falivary, and 

 lacrymal glands. The latter are fimilar on both fides of the 

 body ; but the refemblance cannot be compared, in refpeft 

 to its exaftnefs, to that of the double organs in the animal 

 life. One kidney is lower than the other ; their arteries, 

 veins, and nerves, are not analogous in length or fize ; often 

 various notches exift in one, and not in the other : the 

 lame obfervations will apply to the falivary glands. 



Generally the forms are not determined in a very certain 

 manner in this fyftem : they are fubjeft to innumerable 

 modifications in volume, dlreftion, and the different pro- 

 portions ; and differ remarkably, in thefe refpefts, from the 

 precife and rigorous laws which govern the conformation 

 of the organs of animal life. Take fome one organ, by 

 way of example, from both lives. A fmall brain will be 

 found to poffefs a corpus callofum, thalami optici, and cor- 

 pora ftriata of correfponding fize ; while, on the contrary, 

 ^ large liver often has a fmall lobulus Spigeliij and vice virfd. 



A kidney will often be larger in its nppcr portion onl y, of 

 in the lower. Thefe variations in the animal life affeil t h 

 whole organ : wliile they frequently are obferved in fome 

 part only in the organic. Bichat, who makes this remark, 

 endeavours to explain the faft, by his opinion concerning 

 the neccffity of a harmony of aftion in the animal life. If 

 one fide of the brain were developed more than the other ; 

 if one eye, one ear, or one fide of the nofe exceeded the 

 correfponding organs, the operations of the mind, the fenfe 

 of fight, hearing or fmelling, would be inevitably diflurbed : 

 while the fecretion of bile or urine would go on equally 

 well, although fome particular part of the fecreting organs 

 were proportionally larger or fmaller than the others. The 

 glands, which are furrounded by membranes, as the liver, 

 kidnies, and even the pancreas, are lefs fubjeft to thele 

 variations of figure, than thofe which are contained ic the 

 cellular fubftance, without any membranous covering, as the 

 falifary, lacrymal, mucous glands, &c. Thofe of tiie latter 

 defcription in the mouth, and along the trachea, are never 

 alike in two fubjefts. The parotid fometimes is prolonged 

 over the maffeter, and at others leaves that niufcle uncovered ; 

 varies in its breadth, &c. When either ef a pair of glands 

 isfo difeafed, as to be incapable of continuing its funftion,that 

 on the oppofite fide of the body either increafes in bulk, as 

 we may fometimes obferve in the kidnies ; or its fecretion 

 is augmented. 



The furface of fucli glands as are not covered by mem- 

 branes is uneven and tuberculated ; it may be in contaft 

 with mufcles, vcflels, nerves, &c. even with bones, as in the 

 falivary and lacrymal glands. In general, they are fur- 

 rounded by lefs cellular tiffue, than organs which have con- 

 fiderable motion. That which is in immediate contaft with 

 them is denfe, like the exterior coveringof arteries and veins, 

 but it is not fo firm. It does not ufually contain fat ; and 

 by ifolating the gland to a certain degree, it is analogous to 

 the peritoneal covering of the liver, or to the proper mem- 

 brane of the kidney or fpleen. Anatomifts have very com- 

 monly divided the glandular fyltem into the conglobate 

 and conglomerate glands. The former name denotes the 

 gland-like bodies belonging to the lymphatic fyftem, and 

 was deiigi-ied to (hew that each formed only one mafs. The 

 latter term is moft properly applied to the falivary and lacry- 

 mal glands and pancreas, which are made up of numerous 

 fmaller particles united together. It cannot well be given 

 to the liver and kidnies, which poffefs nothing of a conglo- 

 merate ftrufture ; and thefe, accordingly, have been generally 

 called glandular vifcera. 



Organization of the Glandular Syflem. 



I. Peculiar tijfue of this fyflem. — The glandular tiffue dif- 

 fers from moft others, in poffefling no marks whatever of a 

 fibrous difpofition. Its component elements are not placed 

 by the fide of each other, according to longitudinal or 

 oblique lines, as in the mufcles, the fibrous fyftem, the bones, 

 nerves, &c. ; but they are heaped together, by a kind of 

 confufed, and, as it were, cafual approximation, and adhere 

 together but weakly. Thus, while organs, which poffefs 

 diftinft fibres, have confiderable powers of reiiftance, parti- 

 cularly in the direttion of their fibres, glands are torn eafily 

 by flight degrees of violence. The broken furface is un- 

 even, full of projeftions and depreffions, which diftinguifh 

 thefe organs from cartilage; the rupture of which is gene- 

 rally fmooth. The proftate, tonfils, and mucous glands 

 refill much more powerfully than the liver and kidnies, in 

 which the phenomenon juft mentioned is the moft eafily 

 obfervable. The pancreas and falivary glands are elongated 

 by any diftending force, without tearing ; but tliis circum- 



ftance 



