172 



A. I. DARLING 



mitted light, several zones can ])e identified (Fig. 1). Of these the 

 principal ones are the body of the lesion, with the dark zone lying 

 deep to it while the translucent zone lies deep to the dark zone 

 though it is not always seen. Nishimura (1926) described, in addi- 

 tion to the three zones already mentioned, a first stage of attack 



/ 



^.%l. 



Fig. 1. Ground section of early caries ot human dental enamel, mounted 

 in quinoline. (X 52.) (Reproduced by kind permission of the editor of the 

 British Dental Joiinuil.) 



at the deep margin of the translucent zone, and both he and Gus- 

 tafson ( 1957 ) have placed some emphasis on a zone of translucence 

 just superficial to the dark zone. Most observers agree that all these 

 zones exist, but differ on the importance to be ascribed to them. 



There can be no doubt that these zones represent successive 

 stages in the attack of enamel caries, for the earliest lesions consist 

 of a translucent zone only. After this stage the dark zone appears. 



