The fourfold division of the intermaxilla being granted, it is obvious that a cleft through the alveolus such as that occurring in alveolar harelip happens at one of the two following situations, either along the endo-mesognathic, or through the exo-mesognathic suture, _i. e._ between the component elements of the intermaxilla, as Albrecht declares, or between the maxilla and intermaxilla, as Goethe suggested—a claim which has been vigorously defended by Kölliker against its newer rival. The relative position of the clefts is indicated in the diagrams appended (Figs. 36, 37, and 38). [Illustration: FIG. 36.—Diagram representing the old or “Goethe” theory of alveolar harelip, indicating both central and lateral incisors as developed from one intermaxilla on either side, and the alveolar cleft between the maxilla and intermaxilla. M. Maxilla. IM. Intermaxilla. _i₁._ Central incisor. _i₂._ Lateral incisor. _c._ Canine. _m₁._ First molar. _m₂._ Second molar.] [Illustration: FIGS. 37 AND 38.—Diagrams to represent the “Albrecht” theory of harelip, in conditions where the alveolus contained four or six incisors respectively. EG. Endognathion. MG. Mesognathion. XG. Exognathion. _i₁._ Central incisor. _iₐ._ Accessory incisor. _i₂._ Lateral incisor. _c._ Canine. _m₁, m₂._ 1st and 2nd molars.] Albrecht’s papers on the subject are numerous, and contain a large amount of interesting material which space forbids us to introduce here; and one must refer readers, desirous of knowing more, to the appended list of his chief works.[52] But the arguments in favour of his theory may be briefly stated to be drawn from the following facts: [Illustration: FIG. 39.—Drawing of an adult upper jaw with right-sided alveolar harelip and cleft palate, and the vomer attached to the left palatal margin. A rudimentary mesognathion bearing the stunted lateral incisor is shown on the outer side of the cleft. _i₁, i₂._ Central and lateral incisors, _x._ Inter-endognathic suture. _y._ Exo-mesognathic suture. (After _Albrecht_.)]