178 
THE WORM GROUP 
hairs and later found the “ hair snakes/’ that the hairs grew 
to form the snakes or small round worms. If they had 
been as careful to look before any hairs were put in, they 
would have seen these “ hair snakes ” swimming about. 
A better test is to take a bottle of distilled water, put in 
the hairs, and watch for developments. Such a test would 
show that no hairs turn into hair snakes. 
Hair snakes have a complete life history as clearly defined 
as other worms. They lay eggs which fuse with sperms 
and form larvae. These larvae live as parasites in the bodies 
of insects and fishes and when mature make their way out 
Figure 166. — Hair Worm Living as a Parasite in the Body of the 
Grasshopper. 
of the bodies of their hosts. It would be natural, then, to 
find them in pools where horses drink and these parasitized 
fishes live, or in watering troughs into which grasshoppers 
may have jumped, as they so often do. 
We know at present no way in which lifeless matter can 
be made to live. A hair cannot become a worm and a 
crooked stick cannot grow into a snake. New life comes 
from the old. We sometimes read in the papers that some 
one has produced life from chemicals, but it is not believed 
at the present time to be possible. 
161. The Earthworm is the simplest and best animal to 
illustrate the annelid group of true worms. 
When one examines a living earthworm, the head end 
