192 MICROSCOPIC ANATOMY OF THE TEETH 



seen within the tubes ; these take stains deeply and would, 

 appear to be the elements which separate the lime salts 

 from the blood in the vascular tubes and sinuses, and take 

 the place of the more definite glandular structures seen in 

 Tautoga. 



For further details on the subject the reader may be 

 referred to the original paper (16 d). 



In the paper before alluded to (56) Mr. Thornton Carter refers to the 

 author's description of the enamel organs of Sargus and Labrus, and says 

 his own material lends no support to these views. He did not examine 

 the species described by the author, and however anomalous it may 

 appear there are apparently considerable differences in the mode of 

 development of the enamel within the same family of fishes. There 

 can, we venture to say, be no doubt about the appearances in the enamel 

 organs of Tautoga in Sargus ovis and in the two Japanese fish ; while in 

 another fish belonging to the Labridse, the freshly-preserved head of which 

 was sent him from America, the author could find no evidence of any such 

 change in the enamel organ, which showed, in all the germs examined, 

 the external epithelium and ameloblasts and no penetration by blood- 

 vessels. The whole fish not having been received, it was not possible to 

 identify the species. Mr. Carter says that in Pagellus centrodontus, one of 

 the Sparidse, and in Labrus bergylta, which he examined, although he found 

 the vascular canals in the enamel organ described by the author, he did not 

 find the tubes or gland-like bodies, but persistent ameloblasts. Mr. Carter 

 says the author's figures show no cytological details, but a reference to 

 the photographs will show the presence of cells, although these have no 

 resemblance to ameloblasts or the cells of the external epithelium, but are 

 arranged as are the cells of a secreting gland in definite relations to the 

 channel or lumen which they surround. Their minute round nuclei are 

 also characteristic of glandular cells (see figs. 101 and 103). 



It is scarcely necessary to repeat that the specimens of Tautoga and 

 Sargus were freshly preserved, and the appearances are not due to imper- 

 fect preservation. Whether these cells which surround the central lumen 

 are derived from ameloblasts may be a doubtful point, but in the very 

 large series of slides prepared by the author there was no indication of 

 this, neither was there any trace of the cells of the external epithelium, 

 as the photographs plainly show. Mr. Carter suggests that these views 

 are based on those of C. S. Tomes with respect to the Gadidse, but the 

 observations above recorded were quite independent of these and followed 

 on an attempt to trace the process in Sargus with freshly fixed material, 

 as Tomes considered this to be similar to what he described in the Gadidse. 

 The author was enabled to show that the enamel organ in both the Sparidse 

 and Labridse is penetrated by blood-vessels ; this penetration, as shown 

 both by Mr. Carter and by C. S. Tomes, does not occur in the Hake. 

 To clear up this question much further investigation is required, as the 



