OBLITERATION OF SUTURES IN SKULL 501 



This group includes 725 skulls with a complete milk-dentition. 

 And, proceeding in the same manner as before, it appears that in 

 the whole collection the number of skulls showing a closure 

 of the masto-occipital suture in this group must be at least as 

 follows: Complete obliteration on both sides 16 times, partial 

 on both sides 11. A partial closure on the right side only 20 

 times, and on the left side 21 times, amounting to 68 skulls 

 out of 725. Resuming, we find the following remarkable re- 

 sult. In 1820 skulls varying in age between 3 to 20 years, the 

 masto-occipital suture is obliterated wholly or partially 172 

 times, making about 10 per cent, and in 725 skulls of infants 

 aged 3 to 6 years, the closure occurred 68 times, also coming 

 to about 10 per cent. In this early stage of childhood, the ob- 

 literation is found in the same proportion as in the total number 

 of skulls including the whole developmental period. Hence 

 the following conclusion is obvious: The nmnber of infantile 

 skulls with closure of the masto-occipital suture does not in- 

 crease after the age of six or seven years; the premature ob- 

 literation of the said suture is limited to a circumscribed period 

 of infancy, beginning as a rule before the end of the sixth year. 

 This fact deserves our full attention in reference to its etio- 

 logical interpretation. For the question arises whether this 

 premature obliteration is a pathological phenomenon, or one 

 of a purely physiological nature. When working out my sta- 

 tistical material I doubted at first the physiological nature. 

 I took into consideration the possibility of this process being 

 caused by some inflammation in the neighborhood of the suture, 

 especially in the tympanic cavity. No doubt an otitis media 

 will cause a hyperaemic state in the adjacent parts of the skull, 

 and one can imagine that under the influence of the latter a 

 coalescence of the occipital and petrosal bone may occur. The 

 consideration, however, that certainly not 10 per cent of our 

 children undergo an inflammation of the middle-ear is sufficient 

 to reject the idea of this pathological cause for the obliteration. 

 Moreover there was yet another circumstance pleading against 

 such a supposition. As we will demonstrate in the following 

 paragraph of this paper, the sagittal suture is also very often the 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 17, NO. 4 



