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 

 egg 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 ; 

 1 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 &gg 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 Qgg 

 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 sutHciently 

 far developed to emit sounds. The female then scrapes the 

 sand out of the pit, and after some time the young emero-e. 

 From eggs of this kind, which were exhumed and kept un- 

 covered, the young emerged in three days. 



