MOTOR NUCLEI IN PHYLOGENY 553 
the whole respiratory current is maintained through the action 
of the branchiostegal apparatus (e.g., Lophius). 
This review makes it evident that among teleosts the m. 
adductor mandibulae does not play any important part in 
respiration. Indeed, it is concerned almost wholly either in 
adduction or protraction of the lower jaw or in producing traction 
upon. the maxilla. 
The musculature innervated by the elements of the motor V 
‘nucleus is thus divisible into two quite distinct functional com- 
plexes: one whose action is necessarily of a rhythmic character 
and intimately associated with that of the opercular muscles 
innervated by the motor VII; and another complex, which is 
concerned almost wholly with movements necessary for the 
primary ingestion of food. 
The importance of gustatory stimuli in the reflex activity of 
the respiratory musculature has already been pointed by Kap- 
pers. In many forms, however, the gustatory sense plays but 
little, if any part in initiating the reflex action of the jaw mus- 
culature (e.g., Lophius and the Pleuronectidae) and in such 
forms the influence of visual impressions upon this reflex is 
great. 
The subdivision of the motor V nucleus in most teleosts into 
two groups has already been described but the significance of the 
arrangement becomes increasingly evident when correlated with 
the peripheral conditions outlined above. Thus in Lophius, in 
which respiration is carried on chiefly through the action of the 
branchiostegal apparatus while the opercular musculature is 
reduced to a minimum, the motor VII nucleus is strikingly 
specialized both as to size and position, while the component 
groups of the motor V nucleus are also peculiarly modified. 
The small ventral nucleus in relation to the slightly developed 
secondary gustatory tract evidently may be correlated with the 
slight development of the effector organ with which it appears 
to be associated, viz., the trigeminus opercular musculature. 
The large dorsal cell group, on the other hand, lies in close rela- 
tion to the tecto-bulbar tracts in the laqueus, and in size and 
