")10 A. J. LINOWIECKI 



Simpson ('12), whose observations were made on the raccoon 

 (Procyon lotor Linn) noticed that most of the fibers in the tract 

 after decussating in the posterior part of the medulla, passed 

 into the lateral funiculus of the cord. These were accompanied 

 by a few fibers which were uncrossed and came from the pyramid 

 of the same side. A fair number of fibers from each pyramid 

 ran caudalward, without decussating, in the ventral or anterior 

 funiculus not unlike that in man. From this he concluded that 

 the direct pyramidal tract which was thought limited to man 

 and the anthropoid apes, is present in the raccoon but it dis- 

 appears about the middle of the thoracic region. This location 

 of the pyramidal tract fibers differs from that seen in the cord 

 of the Canadian porcupine (Erethizon dorsatus Linn) . Here he 

 (Simpson '12, '13) employed the degeneration method and then 

 stained the sections according to the ]Marchi technique. After 

 the decussation of the pyramids, most of the fibers crossed to the 

 opposite side and upon reaching the posterior funiculus occupied 

 the anterior or ventral portions of the fasciculi cuneatus and 

 gracilis. Few of the crossed fibers entered the lateral funiculus. 

 A great number of fibers arising from the pyramids do not cross 

 but are continued into the cord in the anterior funiculus along 

 the margin of the anterior median fissure. These form a com- 

 paratively large bundle which is compact. A very scanty number 

 of uncrossed fibers were also seen to lie in the posterior funiculus 

 of the same side. Hence in this animal, the fibers of the pyrami- 

 dal tract are divided into four fasciculi upon entering the cord, 

 viz. : a direct anterior pyramidal tract; a direct posterior pyramid- 

 al tract; a crossed posterior pyramidal tract, and a crossed lateral 

 pyramidal tract. Most of the fibers are found in the crossed 

 posterior tract; then next in number are those in the anterior 

 (direct) tract; next in the lateral crossed tract, and finally in the 

 direct posterior tract. Similar results were obtained by ^Melius 

 ('99) who confined his work to the motor paths in the monkey's 

 cord. He found that after he had divided the tract at the 

 decussation of the pyramids, the vast majority of degenerated 

 fibers crossed to the lateral funiculus of the opposite side while 

 the remainder passed to the lateral funiculus of the same side. 



