279 any form of friction sound I have ever heard. As you have quoted from M. Damoiseau, I may be allowed the same privilege; the third section of his memoir begins thus:" Quel moyen y-a-t-il de s'assllrer de la disparition complete des epanchements pleuritiques" p After discussing the various signs of the absorption of the fluid, he says" L'absence d'egophonie et le retour du bruit respiratoire sont aussi d'excellents signes, mais ils n'ont pas une aussi grande valeur que le
... e, dont la presence est un signe pathognomonique de 1'absence de liquide. Depuis que j'ai fixé mon attention sur ce ph6nomne, j'ai remarque qu'il revetait differentes formes. Ainsi; quelques jours avant d'entendre le bruit du craquement ascendant et descendant avec des sensations diverses de frottement, de cuir, de parchemin, &c. &c., j'ai toujours percu des craquements crepitants, sees, dissemines ou groupes de maniere a faire naitre 1'idee de certains Tales crepitants de la pneumonie, ou du rale crepitant sec a grosses brilles de 1'emphyseme pulmonaire. De jour en jour le phenomene augmente d'intensite, et finit par donner lieu a un veritable craguement ascendant et descendant." From this passage it is quite evident that M. Damoiseau refers to the friction sound so commonly heard after the absorption of the effusion, with which you say you " have been long familiar, and which has been daily taught in Paris for the last eight or ten years by M. Gendrin, and probably by other physicians;" of which I do not in the least doubt, for it has been familiar to myself for the same length of time, and was described very clearly by Dr. Stokes in his work published in 1837, (p. 504,) and I have reason to know was taught by him long before that period. But this friction is as widely different from the sound described by me as occasionally occurring in the lung after the removal of pleuritic effusion, as one physical sign can be from another. I have the honour to remain, your obedient servant, ROBERT MAC DONNELL. Dublin, Lower Fitzwilliam-street, Feb. 14, 1845. %* Notwithstanding the above explanation, we are still of opinion that the symptom described by Dr. Mac Donnell, in his very able and interesting paper, is the same as that described by M. Damoiseau in 1843, lectured on, to our personal knowledge, years previously by M. Gendrin, and long known to ourselves practically. The interpretation of the phenomenon given by Dr. Mac Donnell differs, however, from that which we ourselves, in common with M. Damoiseau, had adopted as the correct one. It is certain that no writers on auscultation or thoracic disease had, before M. Damoiseau and Dr. Mac Donnell, stated in print that after pleurisy a sharp crepitus exactly resembling the crepitus of pneumonia is not unfrequently heard, although there be no other symptom whatever of pneumonia present. This sound M. Damoiseau attributes to a modification of the friction sound, whereas Dr. Mac Donnell considers it to take place in the lung itself, and to be the result of returning respiration in a portion of the lung, the seat of serous congestion. We had thought that M. Gendrin's view of the cause of the crepitus was the same as that expressed by M. Damoiseau, but we find, by a letter which we have just received from M. Gendrin himself on the subject, that we were wrong in this respect. M. Gendrin's explanation is the same as that of Dr. Mac Donnell. He says-" I have long been in the habit of pointing out the humid crepitation which is sometimes heard at the end of pleurisy. I do not know whether this remark belongs to me, or whether I have gathered it from Laennec. I have never attached ' , much importance to it, and scarcely think the priority worth ' , claiming. This sound is produced by the penetration of air in the portion of the lungs which has been compressed during the existence of effusion." We may remark that M. Damoiseau was Interne at La Pitie, the hospital to which M. Gendrin is attached, and may have heard him lecture on the subject as well as ourselves.-Sub-Edit. of LANCET.