VESTIGIAL PARTS. 73 



normal, the tumour occupying the position which should 

 have been filled by the missing teeth. 



That imperfectly developed teeth giye rise to tumours 

 is indisputable ; for instance } the teeth before they make 

 their appearance above the gums are enclosed in a bag, or 

 follicle, formed partly of fibrous tissue or bone. Occasion- 

 ally teeth which should normally be cut and take their 

 position in the dental series, remain hidden beneath the 



FIG. 35. A composite odontome from a Horse, weighing 

 .700 kilograms. 



gums ; in such cases fluid accumulates between the 

 aberrant tooth and its capsules, forming a tumour known 

 as a follicular cyst (fig. 34). 



Sometimes the germs of several teeth coalesce and 

 give rise to an ill-shaped mass of dental tissue known as 

 a composite odontome (fig. 35): in due course this 

 abnormal conglomeration of tooth tissue attempts to 

 rise above the gums, or becomes erupted like an ordinary 



