possess. Care however must be taken, not to confound with tumours an enlarged spleen or liver, a distended uterus or bladder, stomach full of alimentary matter, &c.

In a practical point of view, it is often useful to determine, by means of percussion, whether an enema or a purgative by the mouth is likely to open the bowels most rapidly. If, for instance, there be dullness in the left iliac fossa, in the track of the descending colon, that part of the intestine must be full of feces, and an enema is indicated. If, on the other hand, the left iliac fossa sound tympanitic, and the right sound dull, an enema is of little service, as it will not extend to the cœcum, and purgatives by the mouth are indicated.

Effusion of fluid into the peritoneum may be determined with great exactitude by means of percussion, and the height of the fluid marked, as in the case of pleuritic effusion. In the same manner, a change of position furnishes similar results.

Bladder. This viscus is only to be detected by percussion, when it is more or less distended, and rises above the pubis. It may then be distinguished, and its circular margin limited, by observing the tympanitic sound of the intestines, on the one hand, and the dull humoral sound furnished by the bladder, with increased resistance, on the other. When covered by intestines, it will be necessary to press down the pleximeter with tolerable firmness, but not in such a manner as to give the patient pain. In the infant, the situation of the bladder is not so deep in the pelvis, and a small quantity of fluid renders it cognizable by means of percussion.

A ready approximation of the state of the bladder will be found of great service in cases of apoplexy, delirium, imbecility, paraplegia, &c. &c. In several cases it has been found dangerously distended, on percussing the abdomen to determine the state of the intestines.

I have here only noticed those points and circumstances in the art of percussion which I myself have been enabled to accomplish, and which every one may acquire in a few months by care and attention. The nice and more delicate points I must confess I have myself not yet arrived at satisfactorily, but hope to be enabled to do so by continued practice. To these belong percussion of the kidneys, accurately limiting the left from the right ventricle, determining and marking out the ascending and transverse portions of the arch of the aorta, &c. For directions concerning these points, as well as for numerous details, experiments, cases, and practical remarks, having reference to what has been already noticed, I must refer to the admirable works of M. Piorry.'

1 De la Percussion Mediate, &c., Paris, 1828. Du Procédé Opératorie, Paris, 1831. De l'Examen Plessimétrique de l'Aorte Ascendante, et de la Crosse Aortique,, &c. Archives Gén, de Méd, vol. ix., 1840, p. 431.