10 THE METHOD OF MAKING POST-MORTEM EXAMINATIONS. 



We should notice whether or not the calvarium is symmetrical. The 

 cranial bones increase in size by a growth of bone at the edges of the su- 

 tures. If any suture become completely ossified and closed prematurely, 

 the bones will be unequally developed. The thickness and density of 

 the cranial bones vary considerably within the limits of health. There 

 are often deep depressions on the inner surface of the skull along the 

 sagittal suture, caused by the pressure of the Pacchioniau bodies, and of 

 no pathological significance. We should observe the blood content of 

 the bone, determine the existence or absence of fractures, inflammatory 

 lesions, exostoses, etc. 



The Dura Mater is now exposed. It is more or less adherent to the 

 calvarium ; a moderate amount of adherence, especially in old persons, 

 does not denote disease. Very extensive and firm adhesions are usually 

 produced by inflammation. ]Sear the median line the Pacchiouiau bodies 

 often project through the dura mater and may produce indentations in 

 the internal surface of the calvarium. We must look for clots and for 

 tumors and for inflammatory lesions on the external surface of the dura 

 mater. The longitudinal sinus should be laid open and its contents ex- 

 amined. A circular incision is then made through the dura mater in a 

 line corresponding to the cranial incision ; the falx is divided between 

 the anterior lobes of the brain, and the entire membrane drawn back. 

 We should observe the existence of abnormal adhesions of the dura mater 

 to the pia mater, bearing in mind that a moderate amount of adhesion 

 along the longitudinal fissure is normal. The internal surface of the 

 dura mater is to be examined for the products of inflammation and for 

 tumors. 



The Pia Mater covering the convex surface of the brain is now ex- 

 posed. The degree of congestion, and the existence of serum, pus, or 

 blood, beneath, within, or upon it, are now to be ascertained before the 

 brain is removed. The pia mater in old persons frequently loses its 

 transparency and becomes thick and white ; this change is most marked 

 along the longitudinal fissure and large vessels. Marked and general 

 thickening of the pia mater is the result of chronic inflammation. Along 

 the longitudinal fissure, and sometimes at a considerable distance from it, 

 we usually find small, elevated, whitish nodules, which are the Pacclno- 

 nian bodies and are normal in the adult. 



The amount of serum beneath the pia mater varies. A considerable 

 amount, especially in cachectic persons, may exist without brain disease. 

 Clear serum, raising the pia mater and separating the convolutions of the 

 brain, may be simply dropsical or due to chronic meningitis. Turbid 

 and purulent -serum, beneath and in the pia mater, is due to acute 

 or chronic meningitis. The degree of flatness of the surface of the 

 convolutions should be observed before removing the brain ; for, when 

 marked, it affords an important indication of pressure, from haemorr- 

 hage, inflammatory products, internal fluid effusions, and tumors. The 

 pia mater should be carefully examined for miliary tubercles. 



The Brain. After examining the convex surface of the brain, the an- 



