LIFE'S SIMPLEST CHILDREN. 27 
lime-house. The consequence of this is that wherever 
a thread has been, there a minute hole like a pin-prick 
is left in the shell, and while the animal can draw 
itself quite in out of danger, it can also come out all 
over the shell and take in food. Here, then, we have 
another stratagem taught by life to these her infant 
children. The slime which builds the Globigerina (a] 
or the Rotalia (g] is exactly the same as far as we 
can see as the slime which builds the Miliolite, and 
yet those drops of slime have learnt a new lesson, 
and each one as it is born stretches out its fine threads 
before constructing its shell, thus providing a thou- 
sand openings for the entrance of its food in a house 
not bigger than a grain of sand ! 
And now it only remains for us to ask how long 
these wondrous lime-builders have been upon the 
earth. We ask, and ask in vain, for we have no 
means of counting the vast ages during which they 
have lived and built. One of the largest and most 
complicated forms called the Numnm/ife (from nummus 
a coin, which it resembles), lived 
and died in such millions before Fig. 6. 
the Alps or the Carpathians had any 
existence, that whole beds of lime- 
stone thousands of feet thick and 
stretching over hundreds of miles 
are made entirely of its shells ; 
while the little Globigerina (d, Fig. 
4) and its friends were living and A Nummulitewith 
multiplying in still more dim and open.^^owLg^Ae 
distant periods till their shells accu- chambers. Life size, 
mulated into vast beds of chalk. 
When the ancient Egyptians raised the pyramids 
