328 ELIZABETH CAROLINE CROSBY 
and the other by the Leuden van Heumen method, were used 
to check certain fiber tracts, but the paths described in this 
paper are almost entirely those brought out by the method of 
Cajal. These series were further supplemented by a trans- 
verse series stained with carmine and a second such series stained 
with haematoxylin (both the property of Dr. C. J. Herrick). 
One of the Cajal series was very kindly loaned by Dr. P. 8. 
MeKibben. 
Several specimens were stained by various modifications of 
the Weigert method. While the results were very satisfactory 
for the study of parts of the brain below the thalamus, these 
preparations contributed little of value in the study of the con- 
nections of the cerebral hemisphere because practically none of 
the fiber tracts in this part of the brain at the ages here inves- 
tigated have become myelinated. 
HISTORICAL NOTES 
Rabl-Riickhard (’78) gave an-excellent description and some 
very clear pictures of the gross appearance of the brain of the 
adult Alligator mississippiensis. A brief description of the ex- 
ternal form and some details of the microscopic anatomy of 
the same species were given by C. L. Herrick (90), based upon 
young specimens under 45 em. long. Figures of the alligator 
brain are given in Wiedersheim’s Comparative Anatomy and 
other figures and descriptions of the external form are scat- 
tered throughout the literature and it is unnecessary to enter 
into a detailed account of the gross relations, the essential fea- 
tures of which are shown in figures 1 and 2. DeLange (711) 
presents a series of photographs of surface views of reptilian 
brains, among which are those of Alligator sklerops, and in a 
later paper (713) the same author publishes a series of twenty 
sketches of cross sections through the thalamus and the mid- 
brain of this species. Unger (’11) has given a brief account of 
structure and fiber tracts of the forebrain of young specimens 
of Alligator lucius and Crocodilus niloticus which is preceded 
by an excellent summary of previous work on the forebrain of 
the Crocodilia. 
