PRESENTATION OF THE VERTEX. 291 



centre of the pelvis. The principal diameters of the straits are 

 adapted to the occipito-bregmalic and bi-parietal diameters. The 

 occipito-mental diameter, and the occipito-bregraatic circumference 

 should be parallel to the planes of the openings of the excavation, 

 and to the axes of the straits. These general relations are always 

 to be observed in regular positions of the vertex; but the occiput is 

 far from looking to the same point of the pelvic circle in all cases, 

 whence have arisen the various positions at present admitted in to- 

 kology. 



Antecedently to the time of A. Petit, Solayres, and Baudelocque, 

 accoucheurs were content to say that the occiput had come in front 

 or backwards, that the face was turned towards the sacrum or 

 towards the pubis; and this old method of considering it, which 

 M. Delpech defends, is still generally adopted in England, in Ger- 

 many, and in most foreign countries. It is therefore in France 

 particularly, and almost only in France, that attempts have been 

 made to subject labors to the methods followed in natural history. 

 But upon this, as upon all other subjects that are merely matters of 

 convention, it has happened thai the same fact has not been looked 

 at in the same light by all observers. In the opinion of some we 

 ought to admit six positions of the vertex; according to others, the 

 number may be extended to twelve and even to twenty-four; many 

 think that there should be only four, and some not more than two. 

 Again, those who agree in respect to the proper number differ in 

 regard to the proper method of counting them or locating them. 

 For example, Madame Lachapelle, who like Baudelocque admits 

 of six positions, does not adopt the two antero-posterior positions of 

 that author, but in place of them establishes two transverse positions, 

 &c.; so that it is a pretty difficult matter for students to make a choice 

 in such a conflict of authorities. 



In a theoretical point of view it cannot be denied that the vertex 

 may present itself to every point of the circumference of the superior 

 strait, and consequently, that an infinite number of positions may be 

 established if we choose; but the question is, how many of them 

 would it be useful to adopt in practice, which are those we ought 

 to study with particular care, and not how many we might admit. 

 In the first place, it is evidently superfluous to suppose there are 

 more of them than there are points corresponding to the ends of the 

 four principal diameters of the pelvis; therefore it seems that the 

 number established by M. Flamant, and which unites the classifica- 

 tion of Baudelocque with that of Madame Lachapelle, might be 

 considerably reduced. In fact, the occiput scarcely ever presents in 

 more than two ways to the inferior strait; in one it looks forwards 



