OBLITERATION OF SUTURES IN SKULL 509 



ON THE GENETIC SIGNIFICANCE OF THE PREMATURE OBLITERA- 

 TION OF THE SAGITTAL AND MASTO-OCCIPITAL SUTURES 



The facts, demonstrated in the foregoing paragraphs as to the 

 sagittal and masto-occipital suture, exhibit so much resem- 

 blance in some principal points, that it is desirable to treat these 

 sutures together from a more general point of view. My reason 

 for intercalating these considerations here and for not waiting 

 till the description of the premature closure of all the sutures 

 is given, is founded on the circumstance that in the other sutures 

 premature obliteration is very seldom seen, and does not occur 

 with the regularity which characterizes the two sutures above 

 mentioned. The following points of resemblance between the 

 two sutures may be mentioned. Firstly, the frequency of pre- 

 mature obliteration. Especially in the masto-occipital suture 

 this is so often found, that one may well question why this 

 phenomenon has remained unknown in literature until now. 

 The synostosis of the masto-occipital suture is more frequent 

 than that of the sagittal suture. On the other hand one should 

 not forget that the former suture is paired and the chance of a 

 premature closure therefore is doubled. Secondly, both sutures 

 have the fact in common that the commencement of the process 

 of closure is confined to a circumscribed phase of the develop- 

 ment ending approxunately in the seventh year. By this limi- 

 tation in time the process attains a pecuUar character. There 

 is, as one might say, in the development of man a stage, dur- 

 ing which he exhibits an intensified tendency to obliteration 

 of some sutures. Beyond this stage, this disposition seems to 

 be lost. The weight of this tendency is not at all a small one, 

 as is proved by the fact that a premature obliteration of the 

 masto-occipital suture is seen in more than 10 per cent of the 

 skulls, and of the sagittal suture in 2.5 per cent. This un- 

 expected large number of cases with premature synostosis gives 

 a predominant significance to the problem of the etiology 

 of this anomaly. This question has already been mentioned, 

 i.e., is this synostosis of skull bones a pathological phenomenon? 



In the literature on this subject generally the opinion is ad- 

 vocated that premature synostosis of skull bones is a symptom 



