Notes on the Position of the Fluid in Cases of Pleuritic Effusion

If fluid be effused into any of the large serous cavities, such as the pleural, pericardial, or peritoneal, it is obvious that it must produce some alteration in the anatomical relations of the neighbouring structures. The situations in which the fluid will tend to collect, and the nature and extent of the displacement of the neighbouring organs, are points of considerable practical importance, both in diagnosis and in treatment. The subject does not, however, appear to have received the attention it deserves?indeed, in the majority of works on medical diagnosis it is almost entirely ignored. Last winter session Professor Grainger Stewart read a paper before this Society, " On a Case of Tapping of the Pericardium, and on Tapping of the Pleura in the Treatment of Cardiac Disease," which gave rise to a very interesting discussion. I was, unfortunately, not able to be present on that occasion ; but, after a perusal of the report of the meeting in our Transactions, I must say that this aspect of the subject appeared to me to have been somewhat overlooked. The information derived from the ordinary physical signs, and the usual mode of conducting a post-mortem examination, do not afford a complete and satisfactory knowledge of the position and relations of the fluid. In addition to the theoretical deductions that may be drawn from the application of well-established physical laws, important information may be derived from experimental injections of fluids that afterwards solidify, or by frozen sections in which one or more of the serous cavities