ox THE DEVELOPMENT OF THE TEETH 23 1 



time also the prominences from tlie internal surface of the capsule 

 have enlarged, and have become vascular and more closely adherent 

 to the enamel organ. Some writers have inferred from this appear- 

 ance that the enamel organ itself becomes vascular/ but this is not the 

 fact ; it is simply that portion of the capsule which lies in contact with 

 the enamel organ that presents the vascularity referred to. 



" The dental capsule being originally, as we have seen, a production 

 of the mucous membrane of the alveolar groove, is attached by its 

 external surface to the neighbouring soft parts by means of loose 

 areolo-fibrous tissue. Blood-vessels ramify very freely in this tunic^ 

 and from the interlacement which they then form, numerous capillary 

 loops are given off, which extend into the superficial portion of the 

 membrane. These vascular loops are separated from the enamel 

 organ by a delicate layer of cells, the characters of which have been 

 already explained. 



" Not the least interesting of the features attendant upon the 

 development of the teeth is the relation which the capsule bears to the 

 pulp and to the tooth at various periods of its growth. In the 

 follicular and early periods of the saccular stage, previously to the 

 commencement of the formation of the ivory, the capsule is continuous 

 with the base of the dental papilla ; ^ and at a subsequent period^ 

 when the ivory of the crown forms a complete covering to the pulp„ 

 the same arrangement takes place. But at a more advanced stage in 

 the growth of the tooth, when its formation has proceeded beyond the 

 limit of the crown, the capsule attaches itself closely around the neck, 

 and the connexion of the two structures is so firm, that every attempt 

 to effect their separation generally results in the laceration of the 

 membrane. The continued growth of the tooth carries the capsule 

 upwards with the rising alveolus to the under part of the gum, which 

 now stretches over it ; when pressed upon by the surface of the crown,. 

 it becomes atrophied and absorbed. No portion of the capsule seems 

 to pass down into the alveolus." — p. no. 



Everything that I have seen confirms this admirable description 

 as to matters of fact, and the only objections I shall have to offer are 

 to certain of Mr. Nasmyth's conclusions. 



In Man, then, as in the Skate, the Mackerel, and the Frog, the 



1 Raschkow, in a note appended to his Researches, remarks that he has observed the 

 enamel organ to receive blood-vessels in certain parts, and believes the parenchyma of the 

 organ to be pervaded by capillary vessels. The conclusion which he deduces from this 

 observation is, that the enamel organ was from the l^eginning joined to the capsule. 



- It passes upwards over it, forming a distinct envelope, separated from the layer of 

 mucous membrane externally. 



