Auatuiuioal C'lianges. 691 



substance appears moist and gliatening, reddish in color and 

 may be beset witii liemorrliagic points. In certain cases (Brown 

 and Opliiils, Plutyra & Marek) the cord substance is converted 

 into a grayish-red pulp-like mass in which there is discover- 

 able a reddish-brown track composed of extravasated blood. 

 This can also be seen in neighl)oring parts that are apparently 

 altered to a slight extent only. Pus is found very occasionally 

 only in the cord, and when present it is generally the result of 

 a direct injury. In acute cases there are often sharply circum- 

 scribed areas of hyperemia in the membranes, and even inflam- 

 matory alterations. In chronic cases there may be thickening 

 of the membranes. 



Errors of diagnosis are possible if a thorough examination of the cord is 

 undertaken, and principally because, however carefully it may be taken out, it is 

 scarcely possible to avoid cutting it and the cuts which pass unobserved cause a 

 softening of the substance of the cord and this may be thought to be due to in- 

 flammation. 



Information as to the nature and extent of the lesions can only be obtained 

 by histological examinations. In acute eases the blood vessels appear to be dilated 

 and there is a cellular and in some cases a fibrinous exudate round about them. 

 In many cases the hemorrhagic character of the inflanunation is pronounced, the 

 perivascular spaces being occupied by large groups of red corpuscles, or, as in the 

 cases of diffuse hemorrhagic myelitis observed by Brown & Ophiils and by Marek 

 in the dog, masses of red cells are visible occupying large sections of the cord, 

 the surrounding nerve tissue appearing necrotic. In the nerve cells are to be 

 found all stages of chromatolysis, peripheral disposition of the nucleus, shrinking 

 and disappearance of the cell processes, and even of the cells themselves. There 

 may also be varicose swelling of the axis-cylinder processes, degeneration and de- 

 struction of the medullary sheaths. The diseased parts are rich in cells containing 

 fat. At places where the nervous tissue is destroyed there may be a proliferation 

 of the neuroglia, but in chronic cases there may be a production of fibrous con- 

 nective tissue and a thickening of the vessel walls. 



In cases in which the inflammation involves the whole thickness of the cord 

 the centripetal paths (posterior columns, lateral cerebellar tracts, Gower 's tract, in- 

 dividual fibers of the lateral tract) undergo degeneration towards the brain, and 

 in the centrifugal paths (central motor paths, and, as shown by Dexler and 

 Lienaux, Schultze's tract in the basal portion of the posterior columns) the de- 

 generation proceeds in the opposite direction. In cases in which the inferior cornua 

 are diseased the inferior nerve roots and the motor fibers of the nerves involved 

 also degenerate. 



The disposition and extent of the lesions varies from case 

 to case. The spinal cord may be involved through its entire 

 thickness, or for a short distance only (myelitis transversa- 

 lis), or it may be very extensively diseased, and in still other 

 cases there may be large inflamed areas which do not involve 

 the whole thickness of the cord. In such cases, the lesions are 

 scattered through the tissue (myelitis disseminata). It is very 

 exceptional to find a single inflammatory center (myelitis fo- 

 calis). 



Symptoms. In cases of myelitis transversalis the nerve 

 cells at the seat of the inflammation are killed and the tracts 

 which pass through it on both sides of the cord are inter- 

 rupted. Consequently, there is a peripheral paralysis in the 

 part of the body involved and a central paralysis in parts 

 lying posterior to it, associated with loss of sensation (par- 

 aplegia, para-anesthesia). It is easily understood that the 



