260 J. B. JOHNSTON, The brain of Acipenser. 
et cerebellaris might properly have been shown in this color, since it 
belongs to a more indirect descending path than that constituted by 
the bulbar part of the same complex tract. There are other cases in 
which it is difficult to decide how the fibres of given tracts should be 
classified, e. g. the descending portions of the tractus strio-thalamicus. 
In spite of these uncertainties it is believed that the color scheme 
adopted serves as a valuable adjunct to the description, and that the 
attempt to classify the tracts according to this plan will aid in the 
study of the morphology and physiology of the brain. 
