146 KOLLO E. McCOTTER 



terus. iSince that time it has attracted the attention of a large 

 number of observers, among whom may be mentioned Locy ('05), 

 Brookover ('08 '10), Sheldon ('09) and Brookover and Jackson 

 ('11) with the result that the nerve has been described for nearly 

 all groups of fishes. The presence of the nervus terminalis in 

 Amphibia was studied by Herrick ('09) for the frog and by 

 McKibben ('11) for Urodela. At the last meeting of the American 

 Association of Anatomists at Cleveland, Johnston ('13) demon- 

 strated recontructions of pig embryos showing the presence 

 there of a nervus terminalis which is connected peripherally with 

 the vomeronasal nerves. He also reported having seen the same 

 ner\'e in human and turtle embryos. For a complete history of 

 the nervus terminalis the above references should be consulted. 



My own observations are based in the first place upon six 

 gross dissections of the adult dog and three of the cat; in the 

 second place on the microscopical studies of these fibers after 

 their removal; and thirdly on serial sections prepared to show 

 the median wall of this part of the brain together with the cov- 

 erings and the contained nerves. 



In the preparation of the specimens for the purposes of dis- 

 section the same methods were used as previously described by 

 the author ('12) for the identification of the vomeronasal appara- 

 tus. This method consists of dividing the head to one side of 

 the mid-sagittal plane and immersing the larger part from twenty- 

 four to forty-eight hours in Miiller's fluid to which has been 

 added 5 per cent glacial acetic acid. The nerves are then found 

 to be toughened and differentiated in color, thereby facilitating 

 their identification. The dissection was done under water with 

 the aid of a binocular microscope. The first step in the pro- 

 cedure consists in the careful removal of the falx cerebri and the 

 identification of the vomeronasal nerves which are then followed 

 to the caudal border of the olfactory bulb where the nervus 

 terminalis may be seen associated with it. Then the course of 

 this nerve can be easily traced caudalward. The microscopical 

 study of the dissected nerves was made by dividing the vomero- 

 nasal nerves at the dorsal border of the vomeronasal organ and 

 at their entrance to the vomeronasal formation of the olfactory 



