the separate cusps of dentine were well developed, wliile the 

 spaces* between t!)e several cusps of the tooth were filled with 

 enamel-pulp, wliich was surrounded by a very columnar 

 internal and a Hat external enamel-epithelium. 



As has already been mentioned, a cord of epithelium 

 running in a lateral direction is also present in the case of 

 the first molar. The cord is, however, very little developed; 

 it runs continuously backwards, and at the level of the dental 

 rudiment of the second molar it conies into connexion with 

 the enamel-organ of the latter; but simultaneously it sends 

 oti" inwards a second strong cord of e|)ithelium of considerable 

 length, wiiieh terminates witli a knobbed swelling {vide 

 fig. ^). The swelling is surrounded by close-packed strands 

 of connective tissue, arranged concentrically, and exhibits at 

 its free end two slight indentations, while at the same time 

 in the connective tissue, which lies beneath, the first beginnings 

 of a papilla become visible. The structure does not lie as it 

 might be behind the large rudiment of the second molar, but 

 to one side of it, placed at a considerable distance towards the 

 interior ; and 1 can therefore not regard it otherwise than as 

 the rudiment of a successional tooth. Thus it is demon- 

 strated that the second molar (and naturally the first also) is 

 in its origin in no way different from the teeth lying in front 

 of it. The two first so-called molars ov the upper 



JAW^ BELONG TO THE FIRST DENTITION. 



Shortly after the successional tooth has disappeared from 

 the scene the second molar also disappears further backwards, 

 and no indication appears of the rudiment of the last two 

 molars. It is reserved for further investigations, prosecuted 

 upon more comprehensive material, to display the earliest 

 rudiments of these. 



In the lower jaw the development of the molars has 

 advanced further ; the third molar also is already developed, 

 somewhat smaller, it is true, than the preceding one, but still 

 already provided with all its cusps. Here the conditions are 

 such that, from tlie first molar onwards, an epithelial cord 

 runs uninterruptedly tiirough the posterior portion of the 

 lower jaw, and, fiattened out like a plate, passes above and 

 laterally on the inside of the dental rudiments. It soon 

 conies to pass that this cord has no longer any connexion 

 with the epithelium of the cavity of the mouth, since the 

 latter withdraws more towards the middle in consequence of 

 the growing together of the margins of the upper and lower 

 jaws. At each enamel-organ of the three molars a branch 

 now passes oft' from this broad and very conspicuous epithelial 

 cord, so that in each case the appearance of a dichotomic 



