190 MICROSCOPIC ANATOMY OF THE TEETH 



calcifying enamel, and within this stroma lie numerous 

 irregularly-shaped bodies which would appear to be the first 

 deposit of the lime salts in the form of calcospherites. 

 In Tautoga it appears that not only is the enamel in advance 

 of the dentine in the calcifying process, but a considerable 

 amount of enamel is laid down before any dentine is formed. 

 The line of demarcation between the enamel and the dentine 

 is very evident in the Labridse, as all around the first-formed 

 dentine is a projection which forms the groove into which 

 the enamel fits, as in the Gadidse. The tubular enamel 

 cannot therefore be mistaken for dentine. From the above 

 description it is seen that the glandular tissue has not been 

 produced by any invagination of the epithelial cells of the 

 early enamel organ, as might perhaps have been assumed, 

 but it invades the enamel organ from without. In sections 

 which have been cut in such a manner as to include the 

 mucous membrane of the mouth in the same vertical plane, 

 the connexion of this tissue in the enamel organ with the 

 layers of gland substance immediately beneath the mucous 

 glands on the surface of either the mouth or pharynx is very 

 clearly shown, and many sections demonstrate that this 

 connexion is maintained during the whole period of the 

 deposition of the enamel when this structure has once 

 appeared. 



In the two other species of Labrus examined there are 

 certain modifications of structure which although differing 

 in arrangement would serve the same purpose. 



In Halichceres and in Pseudolabrus no connexion with 

 the glandular tissue of the mucous membrane can be 

 detected as in Tautoga, but the secreting tubes, as we have 

 called them, are much convoluted and alternate with the 

 vascular tubes as in Sargus. In Halichmres the blood-vessels 

 have more the appearance of very thin-walled sinuses, which 

 are of very large proportions compared with the tubes (fig. 108 ). 

 The secreting tubes form loops around the sinuses, and from 

 their lower margins bundles of minute processes extend to 

 the stroma, in which masses of calcospherites are also visible. 

 Fig. 109, from a specimen in which the enamel was retained 

 in situ, shows this arrangement very completely. 



In both Halichceres and Pseudolabrus cellular bodies are 



