The brain of Acipenser. 229 
panded dendrites whose branches break up in numerous glomeruli, 
The neurites of these cells form two bundles, an internal which goes 
to the anterior commissure, and an external which turns outward 
at the posterior border of the olfactory lobe and becomes continuous 
with the lateral fasciculus in the fore brain. This external bundle 
is equivalent to the external root of the olfactory tract in Mammals. 
Within the mitral cell layer is a fibre layer composed of the neurites 
of the large and small mitral cells and forming the internal and 
external roots of the olfactory tract. The granular zone occupies 
all the space between the mitral cells and the ventricular epithelium. 
The granules are spherical cells with usually two processes which 
are sharply characterized by the possession of small spines. These 
processes “are directed toward the periphery and end closely applied 
to the surface of the glomeruli, without penetrating into the interior. 
It is to be noticed that, as the granular zone is much more ex- 
tensive than the others, some of these elements are to be seen which 
seem to have no relation to the glomeruli, since they lie outside the 
area of distribution of olfactory fibres. It is known that these cor- 
puscles are without axis cylinders. In splite of this lack they are 
to be considered as important anatomical factors in the constitution 
of the olfactory lobes, bearing in mind their presence in all Verte- 
brates, preserving their peculiar morphological characters”. Within 
the granular zone is the epithelial or ependymal zone. 
The results of BERDEZ (93) on the frog are known to me only 
through references made by LOwENTHAL (see below). 
I have been unable to secure the paper of P. Ramon (91) on 
the olfactory lobe of Reptiles. 
LOWENTHAL (94) describes the olfactory lobe of the lizard. The 
olfactory fibres divide before entering the glomeruli, and two or more 
fibres may enter the same glomerulus. The glomerular zone con- 
tains small cells whose processes form glomeruli and which possess 
neurites. These correspond to the small cells in this zone in Mam- 
mals. The same cells are present in Amphibia (BERDEZ). Within 
the glomerular zone is a gelatinous layer with large cells (mitral 
cells). These cells are elongated horizontally, not vertically as in 
Mammals, and send several neurites to supply glomeruli. The 
neurites of both these and the small cells have a centripetal course. 
Following this is a layer of nerve fibres and within it a layer of 
grey matter. The cells of this layer are irregularly globular with 
blunt angles. Their processes are relatively few and very slender, 
