84 DISEASES OF THE TEETH. 



' " Lafosse attempts a teratological explanation, but first asks, 

 'If teeth are looked on as arising from the tegumentary 

 System, considering them in most animals as emanating from 

 papillae and mucous membrane, where was the dermoid papilla 

 that constituted the basis of development of this tooth, deeply 

 seated and close to the ear, especially as what might be taken 

 as the crown looked towards the inner surface of the skin?' 



" Further on, Lafosse shows that in certain animals teeth 

 absolutely emanate from the osseous system, such as in the 

 coluber scaber, and other serpents, in which true osseous 

 eminences, coated by enamel, pierce the cesophagean tunics, 

 and project into the tube, whereas they are attached to about 

 thirty vertebras, of which they form the inferior spinous pro- 

 cess. These are intended to crush the eggs that the serpents 

 feed upon. 



"Having established that, as well as developing from 

 mucous membrane, teeth may spring from bone, Lafosse 

 leads us to consider the dental tumours, above spoken of, as 

 congenital, and he looks on them as having sprung from some 

 rudiment of a maxillary bone. In a word, he looks on it as an 

 aberration of development. 'It cannot,' says Lafosse, 'be 

 looked on as an osseous transformation of certain tissues/ " 



A satisfactory account of the morbid developments under 

 consideration is given in the Edinburgh Veterinary Review, 

 page 189, for the current year. The article is entitled 

 " Fistula of the Temporal Eegion," in which it is stated that 

 " M. Macrops has operated on numerous cases of this nature 

 with a happy result. They consist in the development of a 

 dental tumour in the substance of the temporal bone, in 

 front of the ear : leading to the production of a fistula, dis- 

 charging a greyish pus, possessed of a disagreeable odour. 

 The fistula is commonly straight, and opens in the midst of 

 a slight tumour, covered by skin of a hard and warty struc- 



