THE FOREBRAIN OF THE ALLIGATOR ah 
diencephalic fibers, the functional motive for the formation 
of the corpus striatum and the neopallum has been introduced 
into the hemispheres and in the alligator forebrain these somatic 
centers are already beginning to take form and to establish cer- 
tain characteristic and fundamental relationships which will be 
discussed later. 
The specific distribution of the olfactory and the non-olfac- 
tory fibers, the positions and the relations of the various cen- 
ters and, finally, an analysis of these data in terms of their 
functional significance, these are all essential to the adequate 
understanding of the morphology and the evolution of the 
forebrain. The present report is concerned with a descrip- 
tion of these centers in the alligator forebrain and of the fiber 
tracts which put these centers into relation with each other 
and with the diencephalon. Finally, an attempt has been 
made to effect a partial correlation and interpretation of the 
factual data obtained. 
The advice and assistance of Dr. C. Judson Herrick have 
made possible whatever there may be of value in these notes. 
For these things and for the opportunities accorded me in 
his laboratory, I wish to thank him most sincerely. I am 
indebted to Miss Jeannette B. Obenchain for assistance in 
technique and to other members of the Department of Anat- 
omy of the University of Chicago who have given helpful sug- 
gestions. Mr. Streedain has very kindly made the drawings 
of the gross material and has lettered the drawings of the micro- 
scopic material and otherwise aided in preparing them. 
MATERIALS AND METHODS 
The animal chosen for study was Alligator mississippiensis. 
The individuals were small, varying in length from 30 to 55 em. 
The drawings of the surface anatomy (figs. 1 and 2) were made 
from the brain of a 55 em. alligator. | 
The silver impregnation methods of Golgi and Cajal and the 
toluidin blue method were the chief ones employed. Two 
rather imperfect series, one stained with Ehrlich’s haematoxylin 
