ALVINE CONCRETIONS. It sometimes occurs that bodies of a very anomalous kind are passed from the intestines; but the medical practitioner by a careful examination of the substance, and a minute inquiry into the nature of all the ingesta, will frequently succeed in tracing their origin. _Dr. Marcet_, in his “Essay on Calculous Disorders,” relates some interesting instances of this kind, which we shall notice in this place, in order to put the medical man on his guard when called upon to deliver his opinion upon such occasions. The first case is that of some concretions put into _Dr. Marcet’s_ hands by _Sir Astley Cooper_, and which had been discharged by a female patient, under circumstances which made it questionable whether they had proceeded from the rectum, or from the urethra; they were, however, discovered to be pieces of undigested cheese formed into balls by the action of the intestines, or portions of caseous matter actually formed in the intestines from milk taken as nourishment by the person, and coagulated by the gastric juices into those undigestible masses. Another singular species of intestinal calculus was found by _Dr. Marcet_ and _Dr. Wollaston_ to be oat-seeds, derived from the oaten cake which the patient had eaten. _Dr. Marcet_ also describes a concretion which, by the assistance of _Dr. Wollaston_, he discovered to be those small woody knots which are often found in certain pears, and which the person had previously eaten. The last case which he relates is not less curious; a philosophical gentleman of delicate health, and disordered system, voided a number of small red globular bodies, each of which had in its centre two black opaque spots; they were supposed to be peculiar animals connected with his disorder, but _Dr. Wollaston_ soon satisfied himself that they were nothing but the spawn of lobsters, an extremely indigestible substance, of which the patient acknowledged to have eaten about the time he passed these bodies. The author has deemed it necessary to introduce this subject under the present article; for, strange as it may appear, it not unfrequently happens, as _Dr. Marcet_ has stated, that persons apparently respectable, produce bodies, as having been voided, which are wholly supposititious.