In a series of observations published on the third stage of labor where the placenta was delivered spontaneously, the time required for the completion of the delivery was carefully noted, and the results varied from a few minutes to thirty-six hours. With these statistics before us, it is manifestly impossible to place a definite limitation on the third stage and to assert that all cases which pass the prescribed bounds shall be regarded as pathologic, and interference undertaken. In spite of

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... e tendency of the last few years to interfere less and less in obstetric cases without positive indications, it may be safely said that if the placenta is not spontaneously delivered within two hours after the birth of the child, some pathologic condition is present which necessitates interference. Usually the presence of hemorrhage or other symptoms will further an earlier diagnosis, and the question generally lies between two closely related conditions, an"adherent placenta" or " retained placenta," and the differential diagnosis can only be obtained by careful examination. In " retained placenta " the structure is detached and lies within the maternal parts, from which, owing to some obstruction in front or insufficient vis a tergo, it can not be expelled without artificial assistance. The adherent placenta, as its name indicates, is still attached to the uterine surface more or less intimately, either by its entire surface or by certain segments of it, this latter constituting the so-called " partially adherent placenta," which furnishes a very alarming form of postpartum hemorrhage. Tne site of adhesion, according to Nyulasy, is most frequently the fundus, but very often it is near or involves the cervix, as in placenta previa, but there is no regularity in the selection of the site. Frequency.-The usual difficulty in obtaining accu¬ rate statistics in obstetrics is nowhere better illus¬ trated than in attempting to determine the frequency of the occurrence of " adherent placenta." Comparatively few reports have been published from hospitals, and the general practitioner has con¬ tributed almost nothing. Then, too, the available reports are not always satisfactory, as for instance, the " Medical Report of the Society of the Lying-in Hos¬ pital of New York" (1897) shows that the placenta was manually removed 182 times in 9034 labors, or 1 in every 49.6 labors, which demonstrates that manual removal of the placenta is far more frequent there than elsewhere recorded, even if the placenta pre¬ via cases are included in the statistics, as doubtless they are. In the Chicago Lying-in Hospital and Dispensary, the placenta has been manually removed only 6 times in 2529 cases, and only 4 times for " adherent pla¬ centa." Judging from their figures, it would seem that the placenta is less frequently adherent than Dorland's and Hirst's reports would indicate, and that 1 in 500 or 600 labors would be more nearly correct. Howitz, however, in 1000 cases has seen no bad cases of adhe¬ rent placenta. Owing to the immaturity of the placenta and the absence of the usual degeneration, the placenta seems to be adherent more frequently in abortions than at term; thus Bedford Brown found 30 cases in 200 abortions, or 15 per cent. Mortality.-All observers agree that the condition is extremely daDgerous for the mother, the most fre¬ quent cause of death being sepsis, but hemorrhage plays no small part. In Winckel's 50 cases 9 died, or 18 per cent. Hirst gives a mortality of 7 per cent., which he attributes to sepsis. The mortality from sepsis will always preponderate in those cases which are treated expectantly, while the hemorrhage will cause the greatest number of deaths in the recent cases. Etiology.-The origin of the affection is somewhat obscure, but so many concurrent affections have been assigned as causes that it seems best to discuss the etiology under three separate headings: 1. The causes attributed to the placenta. 2. The causes attributed to the uterus. 3. The causes attri¬ buted to the uteroplacental connection. Among the causes attributed to the placenta, it is found that most authors give inflammation of the placenta the first place. There is a diffuse form of inflammation which arises in the connective tissue, and the placenta be¬ comes firm and pale. After the irritative proliferation produced by the inflammation subsides, the connective tissue contracts, compresses the villi, and may result in death of the fetus by diminishing the blood-sup¬ ply, while fatty changes may occur in the placenta, which either becomes prematurely detached or abnor¬ mally adherent. A second form arises in the arteries and adjacent tissues of the fetal placenta and gradually involves the entire organ. As the inflammation proceeds the tissues become indurated and fibrous, adhesions form between the placenta and uterine walls so dense that it is often difficult to distinguish the point of sepa¬ ration post-mortem. Placentitis is an extremely rare disease, and while many cases may and do pass unrec¬ ognized, yet other factors possess etiologic interest. In Brown's series he traced three cases to traumatisms, but these could probably be regarded as cases of pla¬ centitis. He also regards rheumatism as a cause. Syphilis may give rise to inflammatory changes in the placenta, which would produce adhesions, but as many cases occur where neither maternal nor paternal syphilis can be traced, this can only be regarded at most as an occasional cause, as in Brown's two cases. Placenta succenturiata has an etiologic importance from the fact that the main portion of the placenta could be delivered, and the connection between the parts being broken, the smaller portion might remain. Placenta previa is the most common placental anomaly in connection with adherent placenta, which Chazan claims results from the partial loosening of the placenta before labor, whereby the normal mech¬ anism of detachment is interfered with and manual removal is required. His second explanation is more plausible and shows that the placental site being farther removed from the point of greatest contrac¬ tion, less power can be applied by the uterus in pro¬ ducing the detachment. Hence it is only relatively adherent, but this conforms more closely to our knowl¬ edge of the mechanism of the third stage. Again, an abnormally thin placenta, from whatever cause, will be more difficult to expel, because it will double up as the uterus contracts, just as soft glue spread out on the hand will follow the contractions of Read before the Chicago Medical Society, April 26,1899.