THE METHOD OF MAKING POST-MORTEM EXAMINATIONS. 17 



alcohol. In such specimens the fat droplets in the degenerate areas are black, while 

 the myelin is yellowish in color. 



Certain lesions, particularly the softenings of the brain, are best studied by teasing, 

 when fresh, in one-half-per-cent solution of sodium chloride, or in frozen sections of the 

 fresh tissue. The blood-vessels may be stretched on cork with pins and hardened with 

 Orth's fluid or formalin. The eye and portion of the optic nerve, if removed, should 

 be fixed by Orth's fluid and the hardening completed by alcohol. 



For man} r methods of fixation and study which are useful for special purposes, we 

 refer to special works on technique. 



THE SPINAL CORD. 



The examination of the spinal cord is usually most conveniently made 

 after the removal of the brain. 



The body should be placed face downward, with a block under the 

 thorax and the head hanging over the edge of the table. An incision is 

 made through the skin and muscles along the entire length of the spine, 

 and the soft parts are dissected away on each side so as to expose the 

 laminae of the vertebral column. The larninsB are then divided, close 

 within the articular processes, with the saw. 



The saw should be so directed in severing the laminae that the inci- 

 sion shall touch the outer border of the spinal canal, as otherwise the 

 laminae and spinous processes are not easily separated. Great care 

 should be taken on the one hand not to injure the cord with the saw, 

 and on the other completely to loosen the portions of bone to be removed. 

 These, which are the spiuous processes and laminae, are now torn away 

 together, with a stout hook, exposing the cord. 



By means of a long, curved chisel, made for this purpose, the bodies 

 of the vertebrae may be removed from the front after the thoracic and 

 abdominal viscera are taken out, and the cord thus exposed and re- 

 moved. But in this anterior method of removing the cord, as well as by 

 the use of chisel and mallet, bone shears, etc., in the ordinary method, 

 there is great liability of injuring the delicate tissues of the cord and 

 producing, as Van Gieson has shown, ' mechanical alterations which are 

 likely to be mistaken for malformations or the results of disease. 



"When the body has lain on the back, the membranes of the cord may 

 be found considerably congested, without indicating the pre-existence of 

 disease. If the body has lain for some time, epecially in warm weather, 

 serous fluid may have accumulated within the membranes, as a result of 

 post-mortem change. 



The roots of the nerves are now to be cut across, as far away as pos- 

 sible from the cord, and the cord removed in its membranes, care being 

 taken not to press it in any way. It is the safest plan not to grasp the 

 cord itself, but with a forceps to seize the dura mater and thus lift it up 

 at once as it is freed from its attachments. It is now laid on the table, 

 and the dura mater laid open with scissors on the anterior and posterior 

 surfaces over its entire length, and searched for tumors, inflammatory 



1 Van Gieson, "A Study of the Artefacts of the Nervous System," New York Med- 

 ical Journal, vol. Ivi., pp. 337, 365, 421. 1892. 



2 



