Hardesty, Medulla Spinalis of the Elephant. 153 



leaving the nucleus to pass over into the funiculi laterales. In 

 thoracic IV (Fig. 10) the sections show afferent axones from 

 the radix posterior (some perhaps collaterals of such from the 

 funiculi posteriores) entering the nucleus dorsalis more numer- 

 ously than in thoracic VIII. 



In thoracic II a change occurs and with surprising rapid- 

 ity. Figure 14 is given to show the beginning of this change. 

 Numerous afferent axones are seen to enter the nucleus dor- 

 salis of both sides of the section. The nucleus on the right of 

 the figure shows the first indication of the seemingly sudden 

 departure of axones to cross over the cervix of the columna 

 posterior into the funiculi laterales. A few millimeters ceph- 

 alad to Figure 14, the number of these axones increases and 

 their nature and destination become more decided. In Figure 

 15, about I cm. cephalad to Figure 14, the process is at its max- 

 imum, while the nucleus has decreased in size. Adjacent sec- 

 tions show that in the process of leaving the nucleus, these 

 axones pass obliquely cephalad so that in a transverse section 

 their entire course is not shown. At attempt is made to show 

 their general course in Figure 16 which is a summation of the 

 appearances of the nucleus and its vicinity as observed from 

 sections intervening between Figures 14 and 15. The nucleus 

 {Nd.") is shown in its greater size and double contour revealed 

 in its section a few millimeters caudad to Figure 15 (see Fig. 

 14). The axones {C) considered as arising from cell-bodies 

 situated along the extent of the nucleus, cross the cervix of 

 the columna posterior and enter the lateral funiculi, where, 

 coursing obliquely, they are lost. From our knowledge of their 

 behavior in other mammals, we are led to assume that they 

 finally accumulate in the dorsolateral periphery to form the 

 fasciculus cerebello-spinalis (direct cerebellar tract). 



The figures also show an increase in the number of afferent 

 axones entering the confines of the nucleus dorsalis. These, 

 derived from the radix posterior, course ventrally along the 

 mesial border of the columna posterior and, in the cervix, turn 

 toward the nucleus (Figs. 14 and 15 and A., Fig. 16). Their 

 increase In number as compared with sections from more caudal 



