346 MICROSCOPIC ANATOMY OF THE TEETH 



normal situation on the roots of teeth in man. The presence 

 of the large cornified epithelial cells with projecting pro- 

 cesses occasionally seen in preparations of the membrane, 

 would lend support to this view. 



The calcined isolated bodies, above described, sometimes 

 found in the follicle, are within the connective tissue and 

 well separated from the bordering epithelial layers. They do 

 not appear to have the characteristic structure of either bone 

 or cement, and resemble the similar erratic calcification 

 which sometimes occurs in the centre of the connective 

 tissue of the pulp. 



In 1914 a series of papers was published at Milan by 

 Dr. Arturo Beretta of Bologna (1) on the enamel cuticle. 

 The author has not had an opportunity of seeing the original 

 paper, but only a review which appeared in the Dental 

 Cosmos (May 1915). This author concludes that Nasmyth's 

 membrane results from the transformation of the amelo- 

 blastic layer into the basal membrane (probably referring 

 to the clear layer) and of the upper ameloblastic epithelia 

 into areas of granular consistence, which may be called 

 cuticular epithelial remnants. He would thus agree partially 

 with Kolliker's view, so far as the inner transparent layer 

 is concerned ; but it is difficult to understand what is meant 

 by the areas of granular consistence, as preparations of the 

 membrane show a definite layer or layers of cells. He says 

 that the enamel cuticle remains throughout life, and with 

 the advance of age increases in thickness. This statement 

 is hardly in accordance with previous observations. 



Eruption of the Teeth 



The teeth, both of the temporary and the permanent set, 

 are formed deeply in the tissues of the jaw, but soon after 

 the crowns are fully formed take their positions on its 

 upper margin, and the crowns of the teeth are fully exposed 

 within the mouth. The exact method by which this erup- 

 tion of the teeth is brought about has been a matter of 

 much controversy. It seems quite evident that there are 

 several factors concerned in the process, and no one theory 



