Biondi, of Breslau,[51] has completed the observations necessary for the establishment of this fact by demonstrating the four actual points of ossification in many fœtal skulls of different dates, which had been specially prepared for the purpose. Moreover, as mentioned before ([p. 27]), traces of the five intermaxillary sutures, when looked for, may be found in many adult and in the majority of young skulls.
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]).
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.
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: