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CATHARTICS. 



< ATHKTOMKTER. 



HI 



at Hi upper extremity (the mouth) or at it* lower extremity (the 

 rectum) ; many of them, when applied to the akin, or injected into 

 vein, will produce the came effect. This irritation U felt at fint 

 merely by the mucous membrane, but secondarily it excites the 

 muscular coat ao w to increase the peristaltic and vermicular motions 

 of the intestine*. The irritation differs in kind and degree. When 

 it affect* the membrane merely ao far as to occasion a gentle local 

 action, and is followed only by the expulsion of the nutter then 

 retting upon or covering it, without augmenting the quantity or 

 altering the nature of this matter, the agent* which produce such effect 

 are termed laxalim. But if the action be more considerable, and not 

 only the present content* be expelled by their effect, but also the 

 quantity of the secretions of the canal be increased, and their quality 

 perhaps greatly altered, they are termed pwrgativtt : and, according to 

 the particular secretion which they most obviously augment, they 

 receive their appropriate name chologpgues, if it be the bile : hydro- 

 gogue*, if merely the serous fluid. Their effects also frequently extend 

 to the whole system. If their action be very violent, they are desig- 

 nated dnutic purgative*. 



To comprehend fully the manner in which cathartics act, it is neces- 

 sary to direct our attention to the structure and functions of the 

 intestinal canal. This canal extends from the mouth to the rectum, 

 comprising the organs of taste and mastication, of insalivation, the 

 ^nmffh l and the small and large intestines. It is lined with a mucous 

 membrance, the folds or plaits of which increase its surface, while 

 the follicular glands which it possesses pour out a viscid mucus, a 

 quantity of which is essential to the due execution of its office : this 

 quantity is often much increased by certain purgatives, as we see by the 

 glairy mucous stools. Independently of the juices poured from the 

 gland* and vessels into the stomach, the duodenum, or upper small 

 intestine, receives the extremity and contents of the gall-duct and 

 that of the pancreas. Many purgatives in their passage stimulate 

 these ducts, and excite the glands connected with them to increased 

 action. Beneath the mucous membrane is the muscular coat, the chief 

 agent in effecting the propulsion of the contents of the canal. It 

 consists of two set* of fibres, the one arranged in a longitudinal direc- 

 tion, the other in a circular manner. The regular and progressive 

 contraction of these is necessary to move the contents of the canal 

 onwards along its course. The contraction of the one resembling the 

 contractions of a worm in it* progress, is termed rrrmicular, and the 

 other perutaltic. When their contractions do not harmonise, colicky 

 pain* are felt, and are of frequent occurrence during the operation of 

 purgatives, many of which powerfully stimulate this coat to action. 

 When the muscular coat has its action inverted, and the contractions 

 take place from below upwards, instead of from above downwards, it 

 is termed the anti-ptrataliic motion, by which the contents of the 

 intestines are often ejected by the mouth, as happens in ileus and 

 some other disease*. The last coat or serous membrane, called also 

 peritoneal coat, only obey* the lawn of the preceding two in respect to 

 its motion or quiescence. In addition to these structures, the intes- 

 tines receive numerous arteries, and when an irritant affects them, the 

 blood flows thither in increased quantity. The contact of a purgative 

 causes the capillaries to enlarge : the inner surface of the intestines 

 becomes redder, swollen, and warmer a state generally followed by a 

 large increase of the serous exhalation from the extremities of these 

 vessel*. Lastly, the nerve* of the intestines are mostly derived from 

 ganglions of the great sympathetic, by which an important connexion 

 and sympathy is kept up between the intestines, the brain, and spinal 



All part* of the intestines do not feel in an equal degree the effect of 

 a cathartic irritant Some purgative* act more on one port than 

 another, but it may be stated generally that the duodenum, the colon, 

 and the rectum are most under the influence of them. Cathartics also 

 differ essentially in their mode of action, as well as in general in dose, 

 according a* they are derived from the mineral or vegetable kingdom. 

 All those from the mineral kingdom, with the exception of calomel, 

 are neutral salts, and are in their secondary effect pre-eminently anti- 

 phlogistic, while their dose is considerable. Owing to their solubility 

 they are frequently given dissolved in water, which influence* their 

 action. Those from the vegetable kingdom have nearly all a more or 

 leu foHid odour, which often causes the stomach to revolt, and occa- 

 sions nausea. Their impression upon the organs of taste is often bitter 

 and very disagreeable. They generally contain a large proportion of 

 bitter and extractive matters, resins, and gum-resins. Their dose is 

 often very small, from a quarter or half a grain to a very few grains : 

 hence they are often administered in the form of pill, bolus, powder, or 

 electuary, more rarely dissolved in water, sometimes in wine or 

 alcohol, or in the form of extract simple or alcoholic. Several of those 

 from the vegetable kingdom may be applied to the akin, and will 

 produce the usual effect either by rubbing in, as with castor-oil, or 

 spread on the face of a poultice and applied over the abdomen for a 

 short time. Scarcely any articles from the animal kingdom are used 

 as purgatives, though ox-gall and the roe of certain fishes are deemed 

 laxative. Many fruit*, both in their fresh state or preserved, such as 

 prunes, are mildly cathartic. The sudden application <of cold to the 

 mirface of the body frequently has a useful cathartic action. 



By the combination of many purgative substances in the sou. 

 Kcriptiim, their effect is rendered more certain, and at the some time 



milder. It is also frequently very advantageous to combine purgatives 

 with emetics, or with tonic*. 



With respect to the practical employment of purgatives, general 

 rules only can be given here. There is scarcely any disease in which 

 they have not been employed, or at least recommended ; but as much 

 injury may result from their injudicious or unnecessary employment, 

 as good from their careful selection and proper application. The cir- 

 cumstances which call for their use ore either WMN SJB individual, 

 enjoying otherwise sound health, has not that regular' action of the 

 bowels which is at once needful for hi* present comfort and desirable 

 a* a safeguard against disease ; or else when the system is labouring 

 under some other malady, the symptoms of which are aggravated by 

 the retention in the bowels of their contents, which, under such cir- 

 cumstances, ore very apt to be of an unhealthy kind. But as these 

 states may occur in individual of every constitution, and may be 

 accompanied, in the latter case, with many other symptoms which 

 require to be taken into consideration, it is obvious that it is not 

 enough that some purgative medicine be administered : an appropriate 

 selection is necessary. Hence in the course of the same disease (for 

 example, during continued fever), though purgative medicines may be 

 necessary through its whole course, very different medicines must be 

 employed towards the latter stage from those at the beginning. No 

 person unacquainted with medicine would think of treating a case of 

 severe fever, where professional assistance could be obtained, but yet 

 in other diseases, or even where there is no disease, unprofessional 

 persons undertake-to decide for themselves or other* wlu-n ;\ purgative 

 medicine is necessary, and what it should be. The late Dr. Reid stated 

 it as his conviction derived from extensive observation at a dispensary, 

 that one half the children that died in London under two years of age 

 were killed by mothers and nurses dosing them with rhubarb and 

 magnesia. For very delicate children nothing can be worse than the 

 frequent use of magnesia. Even grown up persons may be injured by 

 it, either by its debilitating action, or by its accumulating in the 

 intestines : a moss weighing six pounds has been found in the intes- 

 tines of a person who had frequently used it. Drastic purgatives, 

 especially of a resinous kind, such as acammony or camboge, when 

 frequently repeated, deprive the inner coat of the intestines of its 

 covering of mucus, and excite inflammation, which often terminates 

 fatally. Excessive purging also may result from an over-dose, and 

 plunge the person into such a state of debility as to place him in 

 imminent danger, or even cause death, either immediately or remotely. 



Habitual constipation certainly requires to be remedied, but this is 

 best done by mild laxatives, diet, and proper exercise. When tin- 

 fault is in the rectum merely, enemata of warm water or gruel may 

 be used, for a few times at first, to remove and prevent accumulations 

 in this part of the bowel. But even these apparently simple means 

 should not be hod recourse to without medical advice, as the nature of 

 the constitution of the individual must be taken into consideration, 

 and certain precautions observed. It is frequently serviceable to 

 confine persons of a scrofulous habit to the house during the use of 

 purgatives, as they are peculiarly liable to be affected by cold before 

 their operation has passed off. A layer or roller of flannel over the 

 bowels is beneficial in such persons, especially in winter, during the 

 operation of purgatives. A similar belt is useful in ijionlaneum 

 <liarr>iua, especially t if cholera. .-itln r I Jiglish or Asiatic, be prevalent. 

 The opposite state to constipation, diarrhoea or looseness, is often 

 best treated by purgatives, especially if it arise from the presence of 

 any undigested food, or unhealthy secretions in the intestines. The 

 mucous fever and diarrhoea of children yields to purgatives sooner 

 than to any other means. The some may be said of many spasmodic 

 diseases, especially in children and females ; but as in the treatn 

 these complaints medical superintendence cannot be dispensed with, 

 we deem further remarks unnecessary. (Hamilton 'on Purgative 

 Medicine*,' 8th edit) 



CATHARTIN, the active principle of the various species of t'atria, 

 which are used under the name of Senna. 



CATHEDRAL. Certain churches are called cathedral* or cathedral 

 churches. They are so called in consequence of having a seat of 

 dignity (cathedra, a Greek term for such a seat) appropriated to a 

 bishop or archbishop. Thus there is the cathedral church of Canter- 

 bury, the cathedral church of Norwich, the cathedral church of ' 

 [CHURCU.] They have usually also a dean and body of canons or 

 prebendaries : but thin U not essential to constitute a cathedral church, 

 nor is every church that has a chapter of canons a cathedral church. 

 [liisnor; CANON.] 



CATHETOMETER (from Kcfflrrot, a vertical line, and nirpov, a 

 measure), is an instrument for meamrixg the difference in level (that 

 is, the vertical <li/rre*fr in height) between two liquid columns in 

 equilibrium. It wa devised by Dulong and Petit in the course of 

 tln-ir researches on the dilatation of liquids by heat, and has been 

 improved in form l.y I'ouilli t, who also gave it the name of ratkctometcr. 

 [HEAT.] Regnault has made great use of it in his researches ; and, as 

 M. Jamin observe* in his ' fours de Physique,' " there is no more con- 

 venient piece of apparatus, when it in well managed ; none more falla- 

 cious, v/nen badly regulated." In ito ilmjiltut form, it consists n 

 of a telescope sliding vertically on an upright scale, the motion of 

 which between the two levels shows the difference of their li- 

 . iinplf of its application will be seen under BABOXETKK. 



