Note on The Coroparative thickness of the Skull 

 as an index of brain recession. 



A suggestion. 



By 



R. J. Anderson. 



The thickness of the skull, which depends, as is well-known, 

 amongst other causes, upon the superjacent tissues, the furrows and 

 convolutions, and the position and attachments of the membranes, 

 varies a good deal in the same district for different skulls, and at 

 different periods of life. The convolutions cease to mould the cranium 

 as the latter attains to old age, and the increasing thickness of the 

 skull is attended with the retrocession of the convolutions. The 

 following table gives the results of taking averages of measurements 

 of a series of skulls, the right and left sides compared in order to 

 see whether any marked asymmetry existed, and notes the frequency 

 on both sides and the amount where this was ascertainable. The larger 

 measurements are more satisfactory than the smaller. The individual 

 measurements are given in the Dublin Medical Journal. The larger 

 differences are naturally the fewer. The difficulties that present them- 

 selves in making these measurements are considerable and where the 

 groove formed by an abnormal branch of an artery tends to invalidate 

 the result it becomes necessary to take a measure a little to the side, 

 where measurements were made in sinuses the rule did not apply. 

 Where a thickening is due to the meeting of the bone ridges that sup- 

 port the skull, the measurements were made so as to get free of the 

 thickening. It will be desirable to make measurements of a much larger 

 number, in one thousand skulls at least, to strike instructive averages. 

 Further suggestions with reference to the position of the measurements 

 and the mode of accurately locating them are given below the table 

 erad at the Portsmouth meeting of the British Medical Association. 



