283 
90 cm in length. In this specimen we can identify the same parts 
as in Figs. 7 and 8 and something additional — the distal part of the 
lobe is now converted into bulb (Zob) and its central part into tractus 
(Tr). As development proceeds the tractus becomes longer and slender 
and more nerve-like in appearance, but, it should never be confused 
with the olfactory nerve, which has been carried forward on the distal 
extremity of the lobe. 
As in the earlier 
stages, the olfactory 
nerve consists of 
two main divisions 
(a and 5b) but the 
bundles of each di- 
vision arelarger and 
more sub-divided. 
The median nerve 
(nv) still persists 
and is joined mainly 
with division (a). It 
has increased in 
length along with 
the elongation of the 
lobe but otherwise 
it is similar to the 
condition described 
under Fig. 8. 
A study of sec- 
tions was constantly 
made in connection 
with the dissections. 
Material was pre- 
pared in picro- 
sulphuric, chrome Fig. 9. “X about 2 diameters. 
oxalic and Her- Ä 
MANN’s fluids. Those in picro-sulphuric were more favorable for 
dissections, those in Hermann for study of nerve distribution by 
sections. Very good results were obtained by staining with iron 
haematoxylin. Fig. 10 shows a section through the plane of the 
median nerve (nv) in an embryo 20 mm long, prior to the formation 
of the olfactory lobe. On the right side are shown two independent 
nerve connections with the brain-wall. The median dorsal are is the 
