220 
HAROLD'S DISCUSSIONS. 
One-celled animals must perfortn tlie functions of 
life with the whole body, and they are poorly per¬ 
formed. However, the little creatures seem to enjoy 
life in their own demure way. 
There are many kinds of these unicellular beings. 
Most of them live in water, either fresh or salt. 
Others live as parasites in the larger animals, and 
these in turn in still larger ones, so that in this world 
of little things, as throughout the animal kingdom, 
the truth holds good which is expressed, in reverse 
order, in the following lines : 
“ Great fleas have little fleas, 
And these have less to bite ’em; 
These fleas have smaller fleas, 
So on ad infinitum^ 
