.528 



A J. LINOWIECKI 



TABLE 1 



DIAMETER OF LAROEST 

 MEDULLATED FIBERS 



Rat 



Guinea-pig 

 Rabbit . . . . 



Cat 



Mole 



Monkey . . . 



8.39m 

 12.58m 

 17.44m 

 17.44m 



4.84m 

 11.95m 



DIAMETERS OF MAJOR- 

 ITY OF MEDULLATED 

 FIBERS 



l.O M- 3.23m 



1.39m- 4.84m 



11.3 M-15.6 M 



9.67m-12.27m 



4.8 



9.6 



were intermingled with these, but the average size of the fibers 

 appeared to diminish in proportion to the distance of the lesion 

 downward on the convexity of the brain. 



Rothmann ('10) who experimented with apes (Macacus rhesus) 

 found that the pyramidal tract was situated exclusively in the 

 posterior part of the lateral funiculus. He also employed the 

 degeneration method and could see no degenerated fibers in any 

 other part of the cord and so concluded that no direct pyramidal 

 tract was present. He summarized his paper by saying that the 

 numerous experiments on apes, dogs and cats permit the state- 

 ment that no direct pyramidal tract in the anterior funiculus 

 is present in the higher mammals, man excepted. 



The sections at the level of the third cervical segment show the 

 pyramidal tract not very deeply stained with silver. At the 

 level of the seventh cervical segment and as seen in figure 8, 

 the tract is somewhat more deeply stained and its outline is 

 quite distinct. The axons stand out clearly but their number is 

 small as compared with that found in a similar area of the py- 

 ramidal tract of the rat. The medullated fibers are, however, 

 much larger in diameter, and but few small ones are found through- 

 out the tract. In the thoracic part of the cord, the tract is stained 

 a little deeper than the rest of the white substance from which 

 it is not sharply marked off. Lower down in the cord, no sug- 

 gestion of its presence was shown by the pyridine-silver stain. 



The Pal-Weigert sections showed no difference in the staining 

 quality of the white substance and the outline of the tract could 

 not be made out at any level of the cord. The myelin sheaths 



