62 OLOF LARSELL 



As already stated, the attempt to find strands from the termi- 

 nahs to the blood-vessels of the hmiian brains was not success- 

 ful. Nerve strands similar to those present on the anterior 

 cerebral artery of the beef and the mule were found and small 

 twigs were observed to enter the walls of the corresponding 

 vessels of the human material. Efforts by the gold-chloride and 

 Bielschowsky methods to demonstrate nerve terminations in 

 these vessels were not satisfactory with the material available. 



The studies on the embryonic material did not serve to reveal 

 any features not already known. 



III. SUMMARY AND COMMENTS 



1. The nervus terminalis of mammals is made up in part, at 

 least, of sympathetic fibers, and its ganglionic clusters contain 

 sympathetic cells. The wide distribution and large number of 

 fibers of the peripheral plexus (as noted by Brookover) , in com- 

 parison with the small size of the central connections, resemble 

 the relation of preganglionic fibers to the postganglionic fibers of 

 the sympathetic system. This resemblance is strengthened by 

 the occurrence of pericellular baskets on many of the ganglion 

 cells of the intracranial clusters. 



2. Two types of neurones are present in the terminalis, namely, 

 1) sensory and 2) motor. 



3. Some of the sensory fibers end in the muscular walls of the 

 anterior cerebral artery and its branches by a type of nerve ter- 

 mination hitherto undescribed in cerebral blood-vessels. 



4. There is some evidence that free nerve terminations in the 

 epithelium of the septal mucosa and of Jacobson's organ are also 

 connected with afferent neurones of the nervus terminalis. For 

 the present it is assumed that these free sensory terminations 

 belong to a sensory component of the nervus temiinalis which is 

 distinct from sympathetic afferent fibers which have tenninations 

 in the walls of the blood-vessels. 



The type of nerve endings and their position in the mucosa 

 would seem to indicate that this component is part of the general 

 visceral afferent system. The early embryonic history of the 

 nerve in ganoids and selachians might, however, point to a rela- 



