THE FOREBRAIN OF THE ALLIGATOR 335 
Centers of the hemisphere 
Both basal and cortical centers are found in this region in the 
alligator. The former will be described first. The term olfac- 
tory lobe will be used a number of times in the following de- 
scription. By that term is meant the anterior portion of the 
hemisphere, including the secondary olfactory nuclei from the 
posterior end of the crus to the beginning of the primordial 
general cortex. 
Nucleus olfactorius anterior (figs. 3 to5 and 14). In the crus 
the nucleus olfactorius anterior occupies a ventro-medial po- 
sition. It extends back into the hemisphere and runs caudad 
for some distance.. It is gradually pushed away from the sur- 
face by the cortical layer of the tuberculum olfactorium and 
is directly continuous with the non-cortical part of that nu- 
cleus. Throughout most of its extent in the hemisphere the 
boundary between it and the anterior end of the caudate nucleus 
ean not be defined. Johnston (’15) has described this nucleus 
in the turtle. He considers, however, that it makes up, for 
the most part, just the head of the caudate nucleus. 
So far as has been observed in the preparations made after the 
Golgi method, the cells of the nucleus olfactorius anterior are 
round or goblet shaped and are comparable in form and general 
appearance with the goblet cells of the granule layer of the olfac- 
tory bulb. Figure 29 shows a goblet cell of this nucleus. 
This nucleus is a secondary olfactory center, receiving im- 
pulses by way of the tractus olfactorius and discharging, through 
the axones of its cells, into the tuberculum olfactorium, the parol- 
factory region, and the hippocampus. 
Area parolfactoria (figs. 7 to 9, 16, 17). The cell groupings 
found in the ventro-medial wall of the hemisphere in lower ver- 
tebrates have caused much discussion. Meyer (’95), Unger 
(06), C. J. Herrick (10), Johnston (’13 and 715), and a number 
of other observers have mapped out the cell groups in this region. 
They have not all agreed in regard to the embryological and 
phylogenetic significance of these cell masses and as a result 
a somewhat confusing nomenclature has appeared. 
