68 Dr. A.'Voeltzkow on the Oviposition and 
placed in pits in my courtyard perished through getting 
mouldy, in spite of the fact that only a very small degree of 
moisture could afterwards be detected in the sand. The fresh 
ege is altogether one of the most sensitive objects with which 
I am acquainted. <A slight increase of temperature also 
killed the young embryos to a certainty if the eggs were not 
covered with a sufficient depth of sand. Older eggs, on the 
contrary, are all the more capable of resistance, and may half 
dry up, and lie for days uncovered upon the table, without 
causing the destruction of the embryo. 
The Sakalava people told me that when the young are 
ready to emerge the female scrapes the sand out of the pit; 
I had no reason to doubt this statement, as I had myself seen 
numerous pits from which the sand had been removed and 
which contained the broken egg-shells. ‘This gave rise to 
the question as to how the mother knows that the eggs are 
sufficiently developed and that it is time to scrape out the pit. 
The solution of the riddle was very simple. 
In the workroom of my house there stand a few boxes 
filled with sand containing crocodile eggs, in order that I may 
have the latter always before my eyes and eventually be able 
to see the young animals emerge. One day I heard sounds 
emanating from one of these boxes, and came to the conclu- 
sion that a young crocodile had actually hatched and, being 
buried in the sand, was stifling, and so making these noises, 
On digging out the sand I discovered the surprising fact that 
the sounds actually came from the uninjured eggs. The 
noises are so loud that if the eggs are exposed they may be 
heard quite distinctly in the adjoining room, If the eggs are 
covered with sand, as they are in their natural state, there- 
fore to the depth of about 2 feet, the sounds are somewhat 
deadened, but still distinctly discernible without difficulty at 
the distance of the length of a room. The cries of the young 
animals in the egg can be aroused at any time by walking 
with a heavy tread past the spot where the eggs are lying, 
or knocking at the box containing the eggs, or taking the ege 
in the hand and shaking it slightly ; every disturbance causes 
the young animals inside to utter sounds. 
Since, as mentioned above, the mother animal sleeps upon 
the nest, it will in its movements or in its wanderings to and 
fro between the water and the nest shake the ground, and 
cause those young animals in the eggs which are sutfliciently 
far developed to emit sounds. ‘The female then scrapes the 
sand out of the pit, and after some time the young emerge, 
From eggs of this kind, which were exhumed and kept un- 
covered, the young emerged in three days. 
