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becomes ganglionic; the ganglion on this root forming the anterior, 

 dorso-mesial portion of the complex. This part of the ganglion is, in 

 the adult, distinctly and definitely separate from the posterior portion, 

 excepting only in a few, consecutive, 30 fn sections that pass through 

 the region immediately anterior to the point where the root enters 

 the ganglion. There is, however, even here, no slightest evidence of 

 an interchange of fibres, the two ganglia being apparently simply 

 juxtaposed. Anterior to this point, they are separated by a sheet of 

 fibrous tissue that either represents the ventral wall of the anterior 

 portion of the trigemino-facialis chamber, or a horizontal partition 

 separating that part of the chamber« into upper and lower portions. 



The maxillo-mandibularis root arises by several rootlets, in part 

 from the anterior surface of the projecting anterior end of the medulla, 

 and in part from the mid-lateral surface of the same part of the 

 medulla. The rootlets all run forward and laterally, immediately 

 postero-lateral to the ophthalmicus root, pierce the membranous side 

 wall of the cranium by several openings, and enter the mesial surface 

 of the posterior, ventro-lateral portion of the complex. The rootlets 

 are usually grouped in several bundles, of which the anterior one 

 is by far the largest. 



The motor root of the trigeminus arises by several rootlets from 

 the ventral edge of the lateral surface of the medulla, and quite 

 undoubtedly contains all the motor fibres of the nervus; but, as I 

 have not yet been able to trace the fibres of any of the nerves to 

 their central origin, I can not positively affirm this. It runs forward 

 a short distance close against the lateral surface of the brain, then 

 turns laterally, or upward and laterally, pierces the membranous side 

 wall of the cranium by several foramina, and issues close against the 

 ventral surface of the maxillo-mandibularis ganglion. It does not 

 itself become ganglionic in any part, nor does it receive communi- 

 cating branches from either of the two trigeminal ganglia. 



The fourth root of the complex arises from the dorsal surface 

 of the medulla in the transverse plane of the posterior rootlet of the 

 motor root, the anterior end of the acustico-facialis ganglion here 

 lying between the two roots. It runs downward, laterally, and but 

 slightly forward, pierces the membranous side wall of the cranium, 

 and enters the maxillo-mandibularis ganglion on its dorsal surface and 

 but three or four sections anterior to its hind end, the sections being 

 each 30 y. thick. The nerve that I consider the ramus buccalis 

 lateralis, arises from the dorsal portion of the same ganglion, slightly 

 anterior to this root and directly dorsal to the point where the 



