526 A. .1. LINOWIECKI 



caudalward. This is seen on comparing figure 6 from about the 

 the first cervicjil seguKMit with figure 7 fi'oni somewhat below 

 the middle of the cervical cord. In traversing this short distance 

 it has lost more than half of its fibers. It disappears in the 

 lowest cervical or highest thoracic segments. 



The location of the pyramidal tract in the mole corresponds 

 with that found in the hedgehog by BischofT ('00) . He employed 

 the degeneration method and stained his sections by the Marchi 

 method. The degenerated fibers could be traced, through the 

 brain, from the cortex into the upper cervical segments but 

 beyond that the tract could not be followed. The pyramidal 

 fibers were very fine and had a very delicate myelin sheath. 

 They did not cross at any point during their course but continued 

 on the same side of the cord in the anterior funiculus. 



Monkey {Macacus rhesus) 



In the spinal cord of the monkey (Macacus rhesus) the py- 

 ramidal tract is located in the lateral funiculus. This fasciculus 

 is elliptical in outline, quite large as compared with the trans- 

 verse area of the cord, and is situated in the posterior half of the 

 lateral funiculus bordering medially on the posterior horn, while 

 laterally it extends to within 3 or 4 mm. from the periphery. 

 It is not so sharply differentiated in pyi^dine-silver preparations, 

 as that of the rat or guinea-pig or mole, yet in figure 8, which rep- 

 resents the posterior and lateral quadrant of the cord, its outline 

 is clearly seen. 



Melius ('99) in his work on the brain and cord of the monkey 

 found that the direct pyramidal tract does exist in some monkeys 

 and that it is quite possible for it to vary in individual animals. 

 He also states that the difference in the size of the fibers depends 

 upon the portion of the cortex with w^hich they connect. He ar- 

 rived at this conclusion by employing the degeneration method 

 which showed that degeneration of the largest fibers followed 

 lesions in the highest portions of the brain near the top of the 

 central fissure or the zone governing the movements of the large 

 toe. Not all of these fibers were large, for many smaller ones 



