C Howard Ayers and Julia Worthington 



system curve laterad into the general cutaneous nucleus (Fig, 18), 

 while the lateralis fibers remain behind. As this extreme meso-cephalie 

 part of the nucleus is also the part in which the fibers of the lateralis 

 posterior distribute themselves, as previously stated, it may be called 

 the representative of the lobus Imece lateralis of higher forms. This 

 anterior division of the lateralis anterior supplies certain neuromasts 

 in the tentacles. 



There is a probability that there is still a third division of the 

 lateralis anterior which accompanies the facialis. After the latter 

 nerve has passed through the cranial capsule on its way to the brain a 

 very small bundle of fibers is given off that runs dorsad. Having 

 penetrated about to the middle level of the utricular ganglion, the 

 bundle appears to divide, sending some of its fibers dorsad with the 

 utricular auditory root, and the rest mesad with the utricular general 

 cutaneous fibers. This bundle is difficult to trace; it is almost impos- 

 sible to follow it from the facialis unless the angle at which the sections 

 are cut is favorable. We have not been able to trace its fibers with 

 absolute surety to their entry into the brain; nor have we succeeded as 

 yet in tracing the facialis to its endings in the skin, and consequently 

 cannot state that any of its fil)ers innervate lateralis neuromasts. Lack- 

 ing this confirmation, we do not care to state positively that this small 

 bundle contains lateralis fibers, but can only say that the probabilities 

 are all in favor of this conclusion. If these probabilities should prove 

 to be actualities, then all three of the divisions of the lateralis anterior 

 as found in the higher forms, the two that compose the "Dorsal VII"' 

 of the Amphibian facial nerve, and the hyomandibular branch, are 

 represented in Bdellostoma. 



The Cells of the Nucleus. — "When the acusticus nucleus is studied in 

 sections, it is found that the entering fillers form a central core, running 

 fore and aft throughout its entire extent. Cells are interspersed among 

 these fibers, but the great majority of the cells lie outside of the core 

 as a surrounding cortex, and they are massed in particular dorsad and 

 ventrad of the core. The cells may be divided roughly into two classes, 

 large and small. 



The Small Cells. — The small cells are in overwhelming majority, and 

 are found all through the nucleus. They measure from 5.9 microns to 

 8.5 microns in diameter, and the cell body may be round, pear-shaped, 

 or spindle-shaped. They have large round nuclei occupying nearly the 

 entire body of the cell, and one or more prominent nucleoli. In some 



