THE MOST ANCIENT MEN 373 



deposit caused by water dripping from the walls of these 

 limestone caverns or by streams actually flooding the 

 caverns, the bodies of the men themselves were removed 

 when they died by their friends and families, and buried 

 in the open ground, where they have gradually dissolved 

 and broken up. Only a few here and there of the more 

 ancient races were buried in a cave, and are in conse- 

 quence preserved until the present day. Obviously, it 

 would only be an exceptional honour or superstition 

 which would cause the giving up of a cave to the inter- 

 ment of a dead body, or only rarely that a corpse could 

 be tolerated in the floor of the cave still inhabited by 

 living men. 



It is a mistake to suppose that all the bones of all 

 the men and animals which have lived on the earth's 

 surface are naturally and as a matter of course permanent 

 enduring things. On the contrary, when they are buried 

 in soil or sand permeated by water, they slowly soften 

 and decay, dissolve and disappear. When washed into 

 streams and rivers or into the sea, they break up and 

 dissolve. No bones were dredged up from the floor of 

 the ocean by the explorers of the Challenger expedi- 

 tion. A bone sunk in the sea gradually dissolves. 

 Only those bones (and the same is true of shells) are 

 permanently preserved which happen to get into certain 

 favourable positions, embedded in clay or hard deposit, 

 which is not disturbed, and becomes slowly raised up 

 and free from soaking water before the bone is dissolved ; 

 or, again, those which have been protected in the accumu- 

 lated deposits of the floor of a cavern covered in by 

 layers of hard calcareous slab or stalagmite, which 

 usually is formed by the water dripping from the lime- 

 stone roof and walls. The limestone is dissolved like 

 sugar, and is deposited when the water evaporates 

 " petrifying " the floor of the cave. It is owing to this 



