112 CHARLES BROOKOVER 



tion to the general rule that sympathetic ganglia are derived from 

 neural crest. He found the cells that migrate along a motor nerve 

 (the oculo-motor in the chick) giving rise to the sheath cells of 

 that nerve and contributing neurones to the ciliary ganglion. 

 The case is parallel with the condition found in the olfactory nerve 

 and the nervus terminalis in Amia except that the migration of 

 cells is from the olfactory placode rather than from the neural 

 tube. Also, if it is granted that the cells in the pineal stalk in 

 Amia are sympathetic, we have a case where the sympathetic 

 cells originate from the neural tube direct without any apparent 

 connection with neural crest in development. 



We need further embryological and morphological data, as 

 well as physiological evidence, in order to determine the function 

 of the nervus terminalis. It may contain general cutaneous 

 components along with sympathetic and possibly other elements 

 in some forms of vertebrates. If it is largely vaso-motor, in the 

 forms studied, as I have been led to think from the evidence, we 

 may tentatively consider the fibers of the neurones entering the 

 forebrain as preganglionic. The postganglionic neurones may be 

 considered to be those that put the cells on the olfactory bulbs, 

 and possibly some of those along the olfactory nerve intracranially 

 into connection with the posterior part of the sympathetic on the 

 one hand and with the cells in the nasal capsules on the other. 

 We may summarize the evidence given in various places in the 

 present paper that points to the sympathetic type of the nervus 

 terminalis in Amia, as follows: 



In addition to the point Allis made that the nervus terminalis 

 develops at a time when the ciliary ganglion is developing, we 

 have seen that its development is pari passu with the blood 

 vessels which are always near it in the fishes I have examined. 

 The same thing is true of other forms where the literature men- 

 tions the blood vessels. The cells in the periphery are many times 

 more numerous than the fibers that were found entering the pros- 

 encephalon. These cells are multipolar in some instances and 

 always aggregated into one or more ganglia or scattered like 

 typical sympathetic ganglion cells. The same statement can be 

 made of other forms mentioned in the literature. The fibers of 



