PROBLEMS OF HUMAN DENTITION 133 



third incisor in man shoukl always be considered an atavistic 

 phenomenon. Such a conception however, would be, by its 

 frecjuent occurrence, an error, the increased number of our in- 

 cisors resulting from different causes. After an ample examina- 

 tion of this anomaly in the denture of man and other Primates, 

 it has become clear to me that only the supernumerary incisor 

 arising close to the median line of the palate is an atavistic one. 

 This supernumerary tooth is usually of a conical form, standing 

 most frequently inside the arch. The other supernumerary in- 

 cisors, nearly always standing regularly in the arch, and in most 

 instances possessing a normal incisiform crown, are not at all 

 of an atavistic nature. They are instances of schizogenic varia- 

 tions, as I may call them, because they originate by a division 

 of one of the two normal incisors. They are instances of redu- 

 plication without any historical significance. But, it is an error 

 to deny the historical significance of all variations, simply because 

 there is a group in which the occurrence is due to another factor. 

 I agree fully with the statement of Professor Wilson:^ ''It is 

 beyond question that numerous instances of variation are of 

 purely 'teratological' significance, and the existence of these need 

 not be allowed unduly to discount the value of others w^hich 

 are almost inevitably suggestive of reversion. ' ' There are authors 

 of the opinion that all variations or irregularities in human den- 

 ture, without developmental significance, are symptoms of de- 

 generation, a view with which I cannot concur. If one con- 

 siders these anomalies as symptoms of degeneration, the same 

 must also be done with regard to all anomalies occurring in the 

 other anatomical systems of our organism, the evolutionary 

 nature of which likewise cannot be demonstrated. And certainly 

 there is no morphologist, who will accept this conclusion. I will 

 illustrate this with an example. The sternalis muscle is a varia- 

 tion occurring not infrequently in man, being present in 4.4 cases 

 out of 100. Undoubtedly this occasional muscle cannot be an 

 atavistic one, because it never participates as a normal element 

 in the muscular system of any mammal. That it should be 

 considered a variation of a progressive nature, is equally doubt- 



* Journal of Anat. and Phys., vol. 39, p. 128, 1905. 



