134 ]ME. F. J. COLE OX THE STEUCTUEE AND MOEPHOLOGT OF 



pre-spii-acLilar or chorda tympani divisions of the facial. It also communicates 

 (a) directly with the sympathetic trunk ; (i) by means of Jacobson's anastomosis 

 (see below) with the glossopharyngeus. 



In the adult Cod (see PI. 22. fig. 2) there are two roots to the trigemino-facial complex, 

 but these fu^se in such a Avay that it is impossible to follow the nerves through the point 

 of fusion. Nor is there any obvious ganglion beyond the lateral line ganglion (fig. 2, 

 X. G.). It seems to me to be proiiable that there are lateral line fibres in each root. The 

 roots are separated by the orbital vein. 



Special Description. — The posterior or dorsal root of the trigemino-facial complex, as 

 seen in the sections, arises from the side of the medulla on a level with tlie dorsal border 

 of the horizontal semicircular canal and the j)osterior portion of the infra-orbital sensory 

 canal. Its posterior edge overlaps the anterior edge of the first acoustic root, and it 

 leaves the medulla at a level just dorsal to this auditory root. There is a slight mingling 

 of fibres between the two roots at the point where they emerge from the medulla, 

 but as both roots belong strictly to the lateral line system, this, happily, does not 

 introduce any complication. 



On emerging from the brain the dorsal root swells into an external knob containing 

 ganglion cells ( = dorsal portion of (1) above), and then, internal to this knob, passes 

 straight dowuAvards internal to the vestibule of the ear and alongside and in front of the 

 first auditory nerve. No ganglion cells were seen on this descending part of the root. 

 As the dorsal root passes downwards ventral to the ganglionic projection just described, 

 another root is received which arises anterior and slightly ventral to the first, and passes 

 backwards to join it. At the point where the two roots join is another mass of ganglion 

 cells (= ventral portion of (1) al)0ve), and this second ganglionic enlargement itself 

 becomes augmented by a further collection of cells ( = (2) above) which lies internal and 

 largely anterior to it. In front the three ganglionic masses become closely o^jposed, 

 but the boundaries of all three can be easily distinguished. 



That the trigemino-facial complex is in a somewhat specialised condition may be 

 inferred from the fact that the two roots just described are the only roots for the whole 

 complex — that is to say, they stand for the three anterior lateral line nerves as well as 

 for the trigeminal and facial cranial nerves. The precise course of the fibres of these two 

 roots through the ventral portion of the lateral line ganglion and the trigeminal ganglion 

 my sections failed to demonstrate, but the following facts were made out with tolerable 

 certainty. Setting aside the palatine nerves, which will be found described below, the 

 first nerve to issue from the trigemino-facial ganglion posteriorly is the hyomandibular 

 trunk. Tlie most ventral fibres of this trunk go to form a portion of the facial proper, 

 which is also described in connection Avith the facial ganglion. The passage of the 

 orbital vein splits the hyomandibular trunk into two parts — a postero-dorsal and an 

 antero-ventral. Along the former portion the cells of the second or " trigeminal " 

 portion of the compound ganglion, Avhich have hitherto been entirely intra-cranial, pass 

 outside the pro-otic notch and are spread over the dorsal portion of the hyomandibular 

 trunk outside the cranium and slightly external to the orbital vein. Distal to the vein 



