lOS PROF. DK. L, BOLK 



an observation proving the correctness of the theory advocated 

 in the last section, that our first molar was originally a deciduous 

 tooth. But it does not seem superfluous to point out that this 

 doctrine must be confined exclusively to the catarrhine Primates, 

 and that it fails to hold good with regard to other mannnals. 

 Therefore when I speak of our molars in the present section, I 

 keep in mind only the second and third. 



I do not intend to criticize the different arguments brought 

 up by authors in favor of their theories. The fact that these 

 diverge widely is a clear indication that in this matter no one 

 author has ])roven the correctness of his view in an indisputable 

 way. Therefore I shall confine myself to the results of my 

 direct investigation. 



Originally I was of the opinion that our molars all belong to 

 the deciduous set. This view was based mainly upon the fact 

 that the ontogenetical evolution of our molars occurs in the same 

 manner as that of our deciduous teeth even in the least detail. To 

 com}:»rehend the full weight of this argument I repeat and empha- 

 size the fact that the ontogenesis of the mammalian tooth is a 

 somewhat more complicated process, showing more peculiarities 

 than the usual description indicates. Having first observed 

 these peculiarities in the development of the milk teeth of Pri- 

 mates, and again in that of the molars, it is readily understood 

 that by this agreement I was inclined to the opinion that our 

 deciduous teeth and our molars belong to one and the same 

 dentition. But my opinion of today differs and I shall consider 

 our second and third molars as elements of the second dentition. 



This alteration of my view resulted from the fact that the 

 development of our permanent teeth also shows the complica- 

 tions above mentioned, and in this regard there is not the least 

 difference between the elements of our two sets of teeth. This 

 rendered the basis of my opinion worthless. My present opinion 

 has been formed by tracing the supernumerary teeth in the 

 molar region of man. 



As already mentioned I ha\'e had the rare fortune to be able 

 to examine an extraordinarily large number of skulls. Of these 

 I collected all those with any A'ariation or anomaly in the den- 



