REFLEX ACTION AND DISEASE. 641 



Coughing is adapted for the purpose of expelling irritating substances 

 from the respiratory passages, and thus preventing their injuring the 

 organism, just as the act of winking is adapted to remove injurious sub- 

 stances from the eye. Coughing is usually excited by irritation of the 

 nerves of that part of the body from which the irritant is to be removed. 

 But coughing, like winking, may be reflexly induced by other nerves 

 than those which usually excite it, and thus may prove hurtful instead 

 of useful. Thus, in pleurisy, irritation of the pleura causes the same 

 expulsive efforts as a foreign substance in the bronchi, although those 

 efforts can expel nothing, and only cause pain to the patient ; and even 

 when the act of coughing is induced from the ordinary nervous chan- 

 nels, but where the irritant, like tubercle in the lungs, can not be 

 removed, the act is likewise injurious. In the same way, vomiting is 

 most frequently induced by the presence of irritating substances in the 

 stomach, and proves useful by causing their rejection and thus relieving 

 the stomach of their obnoxious presence. But when the irritation is 

 due to inflammation of the walls of the stomach itself, the expulsive 

 efforts of retching are quite useless, and only exhaust the patient. 

 Here, too, the act of vomiting can be induced by irritation of other 

 nerves than those of the stomach itself. Irritation of the pharyngeal 

 branches of the glosso-pharyngeal and of the pulmonary branches of 

 the vagus, irritation of the hepatic nerves by the passage of a biliary 

 calculus, irritation of the renal nerves by a calculus resting in the kid- 

 ney or passing down the urethra, irritation of the intestinal nerves (as, 

 for instance, by incarceration of a hernia), irritation of the uterine 

 nerves by the presence of a foetus in the womb, or of the ovarian and 

 vesical nerves by inflammation of the ovaries or bladder, may all produce 

 vomiting ; and in all, or nearly all, these cases, efforts at emesis will 

 be productive of no beneficial result. When the irritation is further 

 down the intestine, as when an ulcer is situated in the rectum, there 

 is a constant desire to go to stool, but the only results of the expul- 

 sive efforts involved in its gratification are exhaustion of the patient 

 and aggravation of the ulcerated condition. In the efforts of mictu- 

 rition, as in those of vomiting and defecation, we have combined 

 movements of voluntary and involuntary muscles. The urine is retained 

 in the bladder by the contraction of the sphincter surrounding its neck, 

 and it is expelled by contraction of the bodj' of the bladder itself with 

 the assistance of the abdominal muscles. Both the sphincter of the 

 neck of the bladder and the muscular walls of the organ itself may be 

 reflexly excited to contraction, and we may thus have reflex inconti- 

 nence or reflex retention. One of the most common causes of incon- 

 tinence of urine, for example, is the presence of ascarides in the rectum ; 

 and while the ascarides remain we may employ drugs to cure the 

 incontinence without success. An interesting case is described by Mr. 

 Teevan in the " Practitioner " for October, 1876, where a boy had been 

 treated in vain by medicine, but was at once cured by healing a fistula 



