312 yoiirtml of Comparative Neurology and Psychology. 



The dorsal root of the first spinal nerve is small, entering the 

 caudal end of the first accessory lobe. From the cephalic end of 

 the second lobe a short and broad tract of medullated fibers passes 

 ventrally into the formatio reticularis and dorso-lateral fasciculus 

 (Fig. 9). Here most of the fibers seem to end in the large fasciculi 

 proprii which fill this region and pursue only a short course head- 

 ward or tailward. This tract is merely a concentration of a 

 similar connection found in all of the lobes. The formatio retic- 

 ularis, which under the other lobes is composed mostly of alba, 

 here becomes somewhat more loosely aggregated, with large fasci- 

 culi proprii scattered through a grey field. The grey matter is 

 nowhere extensive. 



As the first accessory lobe merges with the medulla oblongata 

 it shrinks in size and becomes enveloped dorsally by the fibers of 

 the very large spinal V tract. Meanwhile the number of fibers 

 in the dorso-lateral fasciculus diminishes, some passing into the 

 formatio reticularis and others disappearing into a mass of grey 

 which occupies the whole of the median part of the fasciculus 

 (Fig. 10). This mass is the nucleus funiculi. From this nucleus 

 a strong tract of heavily medullated internal arcuate fibers passes 

 ventro-mesially, decussating in the ventral commissure, to reach 

 the ventral funiculus and the ventral cornu of the opposite side 

 at the level of the origin of the first ventral root of the first spinal 

 nerve. 



As we pass forward into the oblongata, just before the level of 

 the vagal lobe is reached, the last vestige of the first accessory lobe 

 disappears and the somatic commissural nucleus shows no longer 

 any distinction between its dorsal and ventral portions. Massive 

 medullated commissural tracts pass between the funicular nuclei 

 of the opposite sides, greatly augmenting the most cephalic part 

 of the commissura infima. There are also broad connections 

 between these nuclei and the formatio reticularis of the same side 

 and the ventral funiculi of the opposite side via the ventral com- 

 missure. 



As we reach the level of the vagal lobe, more than half of the 

 fasciculus dorso-lateralis has terminated in the funicular nucleus 

 and this nucleus itself is rapidly replaced by the vagal lobe (Figs. 

 II and 12). A considerable portion of the dorso-lateral fasciculus 

 continues cephalad into the oblongata, apparently without inter- 

 ruption in the funicular nucleus region. These are probably 



