12 OLOF LARSELL 



tide were made. In this paper Brookover ('17) describes the 

 peripheral distribution of the terminalis in the nasal septum of the 

 human fetus at full term. This material was prepared by the 

 pyridin-silver method. 



A large plexus of fibers is found anastomosing over the nasal 

 septum deep to the main arteries. The writer states that this 

 network ''is so large that it may be considered as hypertrophied 

 as compared to the known development in other mammals, 

 without apparently increasing the central root." There are 

 indications of a sympathetic chain connection with the spheno- 

 palatine nerve and ganglion. 



It seems clear that in selachians, Dipnoi, ganoids, teleosts, 

 Amphibia, reptiles (turtle at least), and mammals there is com- 

 mon to all a nerve with central connections with the brain near 

 the embryonic anterior neuropore, and having a primary periph- 

 eral distribution to some part of the lining of the nasal cavity. 



II. DESCRIPTIVE PART 



Material and methods. The original design of this investiga- 

 tion was to make a comprehensive analysis of the nervus termi- 

 nalis" in the various classes of vertebrates. More difficulties of 

 analysis and interpretation are encountered in mammals than 

 in the other groups, so that the present contribution is limited 

 in its scope to the conditions found in certain mammals, with 

 the expectation of extending these observations in a subsequent 

 paper to other classes. 



The studies were carried on in the Zoological Laboratory of 

 Northwestern University from 1915 to 1918, inclusive, under the 

 direction of Prof. William A. Locy, to whom I express my sense 

 of indebtedness for helpful advice and criticism. My thanks are 

 also due Prof. S. W. Ranson, of Northwestern University Medical 

 School, for valuable suggestions. 



The mammalian material used consists of the following: 



1 longitudinal and 1 transverse series of 10 mm. kitten embryos, fixed in 10 per 



cent formalin and stained with haematoxylin. 

 1 sagittal series through forebrain and nasal septum of kitten one day old, treated 



by the pyridin-silver process. 



