LECTURE VI. 147 



No doubt we ought not to compare abnormal with normal 

 conditions, stiU we may often avail ourselves of them for expla- 

 nation and elucidation ; and it is only in this sense that I men- 

 tion them here, as being, to a certain extent, a key to the 

 process through which the human skull rises from the ape to 

 the human type. 



Let us return to our subject. On examining the facial por- 

 tion of skulls we find a great difference between man and ape 

 in the conformation of the nasal bones and the mode of their 

 connexion. In the ape the nasal bones are broad, depressed, 

 mostly grown together in the middle ; the nasal apertures con- 

 sequently oblique, or in form of a horizontal 8, and, viewed 

 from below, parallel with the apertures of the eyes. But in the 

 gorilla the middle of the nasal suture rises in the form of a 

 little crest ; and in the Negro the nose is so depressed that the 

 difference between the two formations is scarcely perceptible. 

 It , is remarkable that there is also an analogy between the 

 Austral Negro and the gorilla as regards the internal nasal 

 cavities, — the frontal sinuses which are met with in all other 

 races, causing the projection of the region between the eye- 

 brows. These cavities, which are so enormously developed in 

 the elephant, are absent both in the AustraKan and the 

 gorilla, though they exist in the other anthropoid apes. 



The incisors are inserted, in all mammals which have them, 

 in a special bone, the intermaxillary, which is generally recog- 

 nisable throughout life, and remains separated by sutures from 

 those parts of the maxillary bones which contain the canine 

 teeth and the molars. The elements from which the inter- 

 maxillary is developed exist also in man, and are plainly per- 

 ceptible in the foetus. But it soon becomes confluent with the 

 other bones, so that even in the new-born infant the sutures are 

 generally obliterated, and the union with the upper jaw complete. 



At the beginning of this century, when the history of deve- 

 lopment had as yet made little progress, the absence of the 

 intermaxiUary was considered as a specific human character ; 

 and Groethe, assisted by that excellent anatomist, Loder of Jena, 

 took great trouble to point out the error. At present it is only 

 the early union which can be cited; but even this has its 



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