NERVUS TERMINALIS: MAMMALS 55 



brain substance, the one slightly rostrad to the sulcus previously 

 mentioned, the other at a point about 2 mm. anterior to the 

 lamina teniiinahs, and somewhat more than midway between 

 the anterior commissure and the ventral border of the brain. 



As already stated, essentially the same conditions are found 

 on the right side of the same specmien (fig. 42) . Here, however, 

 only two roots were found which enter the brain substance. The 

 larger one (b) enters through the same opening as does one of the 

 blood-vessels of medium size. This was the only case observed 

 in the mule where a nerve strand of the terminalis and a blood- 

 vessel enter the brain together. Other rootlets enter very near 

 the openings through which other blood-vessels pass. The main 

 nerve trunks on both sides are very clearly formed by the union 

 of the roots described, with the possible addition of other smaller 

 ones which may have been torn and lost during the dissection. 



The left nerve was removed from its attachments to make 

 possible a closer study of its structure. As represented in figure 

 43, the three principal roots merge into the smaller ganglion. Ros- 

 trally from this ganglion the nerve is compactly enclosed in a 

 sheath of connective tissue. A few millimeters rostrad from the 

 small ganglion is the larger one previously noted. Continuing 

 forward from this point, the nerve remains as a compact bundle 

 as far as the place where it had been broken in removing the 

 brain from the cranial cavity. 



A very slender blood-vessel (fig. 43, hl.v.) winds around the 

 nerve for the greater part of its course. At intervals this vessel 

 gives off branches which penetrate into the nerve bundle. 



Histological. Sections of the ganglia stained with thiDnin 

 reveal a considerable variety in the form of the ganghon cells. 

 The sections were cut 18 m and 20 m thick, so that the processes 

 could be followed in many instances for some distance. As il- 

 lustrated in figures 44 to 47, all variations of type from simple 

 bipolar, to cells having at least five processes occur. Nmnerous 

 binucleated cells (fig. 47) were observed. Of the 292 ganghon 

 cells which were found in the single ganglion of the right nerve, 

 twenty-seven were binucleated, or 9.25 per cent. Sections cut 

 at 10 M and stained with haematoxylin showed the same types 

 of cells in the two ganglia of the left nerve. 



