HAIR WORM 79 



troughs where horse hairs are also found. Boys, and 

 men too, sometimes put horse hairs in water and then 

 after a few weeks examine the water and find these hair 

 snakes. They conclude, since they put in the 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 iu, they 

 would have seen these "hair snakes ' : swimming about. 

 A better test is to take a bottle of water, put in the 



Figure 79. — Hair Worm in Body of Grasshopper. 



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 de- 

 fined as other worms. They lay eggs which fuse witli 

 sperms and form larvae. These larvse live as parasites in 

 the bodies of insects and fishes and when mature make 

 their way out 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 



