The following are the results of his researches: Among twenty-seven cases, (twenty-five vertex and two breech presentations), in which the scalp showed marks of pressure exerted by the pelvis, he found: A single mark of depression, nineteen cases. A double mark, five cases. The double depression was on the same side in three cases. Triple depression occurred in two and quadruple depression in one case.
These thirty-nine depressions were situated as follows: a. On the posterior aspect of the head, thirty-two times; especially on the parietal bone, twenty times; on the forehead, nine times; in the breech cases, on the posterior coronal suture, twice; on the posterior temporal, once.
b. Directly on the sagittal suture, once.
c. On the anterior surface of the head, five times; notably on the fore head or the frontal suture, twice; on Gasser's anterior fontanelle, once; on the parietal bone, three times.
Out of 160 vertex cases, the occiput was depressed beneath the parietals, 122 times; beneath one parietal only, 14 times. The occiput projected above the parietals, twice. In the other cases the overlapping was insig nificant. The frontal was overlapped by both parietals 105 times. One half of the frontal was above, and the other below the corresponding parietal bone in six instances. The frontal was beneath the parietals once. In the other cases the overlapping was slight, unilateral or absent. Over lapping of the two sides of the head:—The posterior parietal was situated beneath, 79 times; the anterior one, 36 times. Both on the same level, 41 times. The other cases not noted. The frontals were generally at the same level. However, the posterior was lower than the anterior 21 times, and the anterior lower 21 times. Olshausen has reported 17 cases of depression of the posterior and three cases of depression of the anterior *ietal.
Matthews Duncan does not admit, as does Dohrn, the action of the promontory, but that of the posterior wall of the lower half of the pelvis, for in normal labor, the pressure experienced by the head against the promontory is insignificant. It is only in the depths of the pelvis that the pressure becomes considerable. According to him, the two oblique distortions of Dohrn, one of which is lateral and the other vertical, are one and the same. The vertical distortion, viz., the flattening of the posterior parietal, and the exaggeration of the vault formed by the ante rior parietal, results from the resistance of the posterior pelvic wall.
The lateral oblique distortion of Dohrn is only a part of the whole distor tion. It depends on the obliquity of the head (Solayres de Renhac), and on the fact that the head rotates while this distortion is being developed. Playfair and Barnes have sought to show that the diameters 0. M. and 0. F. may be increased more than an inch by prolonged labor, while lateral compression may reduce the diameter B. P., even to the length of the inter-auricular diameter. Schroeder accepts Dohrn's view, and adds, that the liberation of the head with the occiput depressed, as happens in the usual cranial presentations, entails this consequence, that the cra nium is compressed, during labor, as regards the sub-occipito-frontal diameter, while it may be elongated in the mento-breginatic diameter. Besides, the cranium is compressed by the floor of the pelvis, in a trans verse direction. While the forehead is descending, the occiput assumes a cylindrical or more pointed form. The diameters S.M.B. and B. P., are shortened and the diameters 0. M. and 0. F. elongated. The pressure of the pelvic floor against the posterior parietal bone, particularly in con tracted pelves, produces a flattening of this posterior parietal, while the anterior parietal becomes more convex. Finally, the cranium of the new born may present a lateral displacement of the two halves of the cranium, as regards each other. This is attributed, by Dohrn, to the pressure of the promontory, but is considered, by Stadfelt and Schroeder, as due to a congenital scoliosis of the cranial vertebra. Spiegelberg considers the dis tortions of the cranium as due to compression in the direction of the diameter S.O.F., exerted by the narrowest part of the genital passages, and to an elongation of the diameter 0. M. Kuneke successively studies the condition of the fontanelles, the bones and the sutures, and considers the form of the cranium as the resultant of what he terms the vital and the mechanical forces. He seeks to show that the shape assumed by the cranium, is due to compensatory and to absolute phenomena. The latter consist in a diminution of all the cranial dimensions. His conclusions are as follows: Posterior Vertex Presentation.—Normal presentation. The occiput is elongated and pointed. The head becomes cylindrical or pointed. The anterior parietal, not the posterior, is flattened (diagonal flattening of Dolan). Finally one parietal slips in front of the other.