ON LATERAL PRESSURE. 165 



between them and the maxillary bones, where the 

 following circumstances are found to exist at the 

 period when the second dentition commences : 



"1st. If the maxillary arch be well formed, suffi- 

 ciently expanded, and of a semicircular form 

 rather than elliptical. 



" 2nd. If the temporary teeth, although broad, 

 are a little separated from each other ; especially 

 if, having been originally somewhat crowded, they 

 have been gradually acquiring more room during 

 the last year or two; as this indicates a disposition 

 in the jaws to expand,** 



The preceding passages, together Avith others 

 of a similar character, in which peculiar effects are 

 alluded to without reference being made to any 

 particular cause from which they would be likely 

 to result, many years since arrested my attention, 

 and led to a closer examination of the subject, 

 with a view to determine the primary source 

 whence these deviations are produced. That there 

 should be a disposition in the jaws to expand in 

 some cases and not in others, was too significant a 

 hint to be lost sight of; as it affords a clear indi- 

 cation of the existence of some peculiarity which is 

 not common to all. Therefore, when we find that 

 the semicircular form of denture, the form which 

 gives rise to a separation of the temporary teeth 

 by the " expansion of the jaws," is invariably 

 accompanied by a broad and shallow palate, this 

 would naturally suggest itself as in some measure 



