480 DAVIDSON BLACK 
In this connection it is of interest to recall Worthington’s 
observations (q. v.) that Bdellostoma possesses but two charac- 
teristic reactions toward injury or discomfort, viz., wriggling 
(swimming) and casting off slime (c. f. common type of total re- 
sponse of Amblystoma larva, Herrick and Coghill, 1. c.). 
The fasciculus longitudinalis posterior is but slightly devel- 
oped, as may be expected, and practically all the chief secondary 
correlation tracts course in the formatio reticularis of the ventro- . 
lateral area of the bulb. 
The tractus tecto-bulbaris et spinalis (laqueus of Holm) is 
without doubt primarily olfactory efferent in character since the 
so-called midbrain is comparable in but few, if any, respects 
with the structure bearing this name in higher forms. The 
chief afferent connections of the midbrain are from the habenular 
nuclei and the base of the forebrain, both of which are olfactory 
nuclei. The laqueus descends through the brain stem in the 
ventro-lateral area and passes into the cord. According to 
Holm’s descriptions and figures, this tract in Myxine lies about 
midway between the raphé and the viscero-motor column. 
The so-called cerebellum has its chief afferent connections by 
way of the tractus olfacto-cerebellaris from the floor of the 
forebrain and by crossed and direct fibers from the acoustic 
nuclei of the medulla. The greatest efferent path from this 
region is the tractus cerebello-spinalis which passes through the 
upper part of the general cutaneous nucleus and then courses 
in the lateral part of the formatio reticularis beneath this 
nucleus. 
A tract from the interpeduncular region, also olfactory in 
character, passes down an indefinite distance in the ventral 
formatio reticularis of the medulla. 
The arrangement of these tracts, ete., is illustrated diagram- 
matically in figures 1 to 6. 
The ventro-lateral formatio reticularis thus contains the chief 
olfactory projection paths. Dorsal to this region, the great 
general cutaneous area and the subsidiary communis and the 
acoustico-lateral centers are located. Between the overlying gen- 
eral cutaneous area and the ventro-laterally placed olfactory paths, 
the whole viscero-motor column in Bdellostoma is situated. 
