230 J. B. JOHNSTON, 
and always rise toward the periphery. All processes have the same 
appearance, an axis cylinder can not be distinguished. The branches 
of the processes can be followed to the immediate vicinity of the 
glomerular layer. The processes are provided with spines. The cells 
are the same as the granule cells of Mammals, with which they agree 
in having a small number of long filiform processes, in that the 
axis cylinder is not recognizable, and in forming many superimposed 
layers. Within this layer is the ependymal epithelium. 
EDINGER’s description (96a) of the olfactory apparatus in 
Reptiles presents some important points of difference from the de- 
scriptions of other authors. He divides the olfactory lobe into 
two main layers or zones, a formatio bulbaris on the exterior, and 
a lobe proper consisting of a cortex continuous with the cortex of 
the fore brain. The cells of this cortex are poorly impregnated but 
are like the small pyramidal cells of the fore brain cortex. For 
exact description of the olfactory lobe E. recognizes seven layers 
from without inward: 1) fila olfactoria, 2) glomeruli, 3) mitral cells, 
4) layer of fibres from the mitral cells, 5) cortex, 6) fibre layer of 
cortex, 7) ventricular epithelium. In comparing this with the fore 
brain cortex he says that the mitral cells are equivalent to a variety 
of pyramidal cells whose dendrites go to meet the fila olfactoria as 
do those of the pyramidal cells to meet the tangential fibres. The 
mitral cells, however, like many cortical cells send off only fibres 
which end within the cortex. The fibres from the mitral cells form 
two tracts, a tractus bulbo-corticalis to the cortex of the olfactory 
lobe and to the area parolfactoria of the fore brain; and a tractus 
bulbo-epistriaticus. EDINGER is somewhat in doubt whether any 
fibres run directly from the bulbar formation to the epistriatum, that 
is, whether the second tract really exists. From the cortex of the 
lobe and from the area parolfactoria a second set of fibres pass 
on to the epistriatum, constituting a tractus cortico-epistriaticus. It 
is difficult or impossible to distinguish between the origin of these 
latter fibres in the lobus cortex and the fibres of the tractus bulbo- 
corticalis. The ending of both in the epistriatum is very clear. The 
remaining tracts described by EDINGER may best be considered in 
later paragraphs dealing with the area parolfactoria, cortex, and 
tracts to the ganglia habenulae. 
In Mammals the work of numerous investigators has established 
the following facts. The olfactory fibres branch as they enter the 
olfactory lobe and may enter two or more glomeruli, fin which they 
