MOTOR NUCLEI IN PHYLOGENY 237 
In the latter animal this nucleus forms a slim well marked cell 
column which extends rostral from the cervical motor column 
into the medulla for some distance above the exit level of the 
first hypoglossal rootlet (fig. 16 C, p. 260). Caudally the nucleus 
ventralis occupies a dorso-medial position within the gray reticu- 
lum of the cervical motor column, in which its identity becomes 
gradually lost. Undoubtedly some of the root fibers arising in 
this nucleus present a crossed relationship. 
As in Cacatua, the nucleus intermedius in Ciconia may be 
readily distinguished throughout its course from the ventrally 
situated cell clusters constituting the nucleus ventralis XII. 
In Ciconia, however, the nucleus intermedius is not a nucleus of 
origin for hypoglossal rootlets only, but, on the contrary, it is 
a cell complex in which arise both vagal and hypoglossal fibers. 
In this form, therefore, we have to distinguish two component 
cell groups in the nucleus intermedius, viz., the pars hypoglossi 
(nucleus intermedius XIT) and the pars vagi (nucleus intermedius 
X) (fig. 2).3 Though intimately associated, the courses of their 
root fibers enable the limits of these two nuclear components of 
the intermedius cell group to be distinguished with considerable 
accuracy, and for this reason they have been plotted as separate 
entities on the reconstruction chart (fig. 16 C, p. 260). 
In Ciconia comparatively few of the fibers composing the 
hypoglossal nerve have their origin in the cells of the nucleus 
intermedius XII and the cross-sectional area of the entire inter- 
medius cell complex is at all levels much less than that of the 
adjacent dorsal motor vagus column. 
In these characters Ciconia presents a marked contrast to 
Cacatua. On the other hand, the hypoglossal origin in Ciconia 
closely resembles that described by Kappers in Colymbus, Casua- 
ris, and Spheniscus (34). 
A third mode of hypoglossal origin has been described by 
Brandis and other investigators, who have shown that in some 
birds the XII nerve apparently may arise in its entirety from 
the rostral prolongation of the cervical motor column (nucleus 
3’ The latter term is synonymous with the Brandis vagal portion of the com- 
mon vago-hypoglossal nucleus. : 
