THE FOREBRAIN OF THE ALLIGATOR Byi7h 
D. Cortical centers 
1. General cortex (in part) 
Primordial general cortex (a special portion of this area in close 
relation with the dorso-lateral area) 
The basal olfactory centers of the telencephalon will be seen 
to be separated into two broad groups. In the first group are 
those of the medial, intermediate and lateral areas which serve 
primarily as secondary olfactory centers. These are old in type, 
having their representatives in the hemisphere from cyclostomes . 
(Johnston, ’12, Herrick and Obenchain 713) up through the ver- 
tebrate series to man. They were originally simply a place of 
synapse and consequent redistribution of incoming olfactory 
impulses. 
The second group of basal olfactory centers includes those 
which have developed within the hemisphere later in the phylo- 
genetic history as a place of correlation between olfactory and 
non-olfactory impulses. It is significant that some of the centers - 
(as for example the tuberculum olfactorium), judging from 
their fiber connections, are both secondary olfactory nuclei 
and correlations centers for olfactory and non-olfactory impulses. 
It is the forward growth, then, of non-olfactory fibers from the 
diencephalon into the secondary and tertiary olfactory centers 
of the hemisphere which has given the impulse toward differ- 
entiation to the telencephalon. These nuclei of the hemisphere, 
which serve as correlation centers for the olfactory and non-ol- 
factory impulses, represent the beginning of that: higher differ- 
entiation. Yet these basal centers do not form true cortex. 
In the Amphibia (Herrick, ’10) in the ventro-medial part of the 
hemisphere, centers showing such type of correlation are pres- 
ent and the medial forebrain bundle, which opens the possibil- 
ity of connection between the olfactory centers and the visceral 
centers in the hypothalamus, is well developed. In the dorso- 
medial part of the hemisphere of Amphibia the material, which 
is the primordium of the hippocampus, is present; it is under the 
influence of olfactory fibers and, to some extent, of fibers of the 
ventro-medial area of mixed function as just indicated. But 
here no clearly developed cortex is found and it is not until the 
