I94 THE AMERICAN NATURALIST. [Vor. XXXV. 
so that no difficulty was experienced in keeping the eggs 
at a sufficiently high temperature. By very careful watching, 
the temperature of the eggs was kept fairly constant, the 
extremes being 32? C. and 40? C. In spite of this care, the 
embryos within the eggs were kept alive only a little over one 
week, and whether they were killed by too great heat, too little 
air, or too great variation in temperature, it was not easy 
to decide. It would seem that in nature the eggs must be 
subjected to a much greater range of temperature than they 
were in this case, so it seemed probable that it was lack of air 
that caused the death of the embryos. 
Towards the end of August a second lot of eggs was 
received, but the contained embryos were in such an advanced 
state of development that most of the eggs were opened and 
the young alligators preserved for anatomical study. "When 
the shells were opened the young alligators would wriggle out, 
snapping their little toothless jaws and blinking their eyes, 
although there was still a mass of unabsorbed yolk protruding 
through the abdominal wall as large as a pigeon's egg. 
A few of these eggs were packed in a small box of damp 
humus, to prevent drying, and were kept in an incubator at a 
temperature of 37? C. On opening the incubator a couple of 
weeks later, curious squeaking sounds were heard coming from 
the inside of the eggs, the sounds which, in nature, tell the 
mother that her young are about ready to hatch and should be 
helped out of the mass of earth and leaves in which they are 
buried. These sounds are audible at a distance of fifteen 
yards or more, so that even when the eggs are buried in the nest 
the parent is probably able to hear the call of her young. The 
next day after the first sound was heard one of the alligators 
broke out of its shell, and a couple of days later two more 
hatched; the rest of the eggs proved to be infertile. 
During the act of hatching, the young alligators would snap 
at the fingers, or any small object, quite savagely; but after 
finally escaping from the egg they could not be induced to do 
so. The umbilical scar persisted for some time after hatching, 
but gradually disappeared. The alligator is about 20 cm. in 
length when hatched, and that an animal of its bulk should 
