216 THE OPEN BOOK OF NATURE 
his ‘‘ works ” distinctly. It is a big lower body in 
comparison with the small head. Observe the kind 
of pumping, expanding, and contracting organ ; 
that is the heart. You can feel the beating of your 
own heart, but the palpitation of the Water Flea’s 
can be seen! That darker organ turned upwards at 
the extremity is the stomach. Our specimen is a 
male ; perhaps we can secure a female, in which 
event we may be able to see the eggs, which are often 
to be observed filling a space in the lower body 
towards the back. The Water Flea has five pairs of 
legs, and his body is protected by a delicate shell. 
I am sure you will agree with me that you have 
before you a well-organized creature, one exquisitely 
adapted to its mode of existence. Its shell makes 
it an ‘‘ armoured cruiser,” and its organization 
shows it to be fairly high in the scale of creation. 
Perhaps you think it interesting for the animal to 
be transparent, and consider it might be an advan- 
tage if we could see the organs of our own bodies 
so clearly : certainly we should be better able to tell 
when there was anything wrong with our “‘ works’”’! 
But if we cannot be transparent in body, we can 
have clear minds, in which we hide no mean motives 
and wrong thoughts. 
To be correct, the Water Flea is not a flea ; it is 
a Crustacean, allied to the crabs, and of the crab 
fellowship. It has been called a flea because of the 
jerky, flealike manner in which it propels itself 
through the water ; it seems to progress in a series 
of jumps. Our specimen is the common Water Flea 
(Daphnia pulex); several other species are to be 
found. The Water Fleas live in fresh water, and 
