The Development of the Alligator 227 
which a liberal grant of money to defray the ex- 
penses of the expedition was received. 
The writer also desires to express his appreciation 
of the numerous courtesies that he has received 
from Dr. Samuel F. Clarke, especially for the loan 
of several excellent series of sections, from which a 
number of the earlier stages were drawn. 
In preparing the material several kinds of fix- 
ation were employed, but the ordinary corrosive 
sublimate-acetic mixture gave about the most 
satisfactory results. Ten per cent. formalin, 
Parker’s mixture of formalin and alcohol, etc., 
were also used. In all cases the embryos were 
stained in toto with borax carmine, and in most 
cases the sections were also stained on the slide with 
Lyon’s blue. This double stain gave excellent 
results. Transverse, sagittal, and horizontal series 
of sections were made, the youngest embryos being 
cut into sections five microns thick, the older 
stages ten microns or more in thickness. 
THE EGG 
FiGurRES I, 1a (PLATE VI.) 
The egg (Fig. 1) is a perfect ellipse, the relative 
lengths of whose axes vary considerably in the 
eggs of different nests and slightly in the eggs of 
the same nest. Of more than four hundred eggs 
measured, the longest was 85 mm.; the shortest 
65 mm. Of the same eggs, the greatest short 
