164 ROUNDWORMS— THE NEMATHELMINTHES 



lymph spaces when infected regions of the body are cut open. After 

 mating, the females release live larvae into the lymph because the eggs 

 hatch before they are laid just as was the case with Trichinella. These 

 tiny larvae are only about a hundredth of an inch long and are carried 

 to the blood. Here they await the bite of a mosquito that might spread 

 them to another person. In most parts of the world, the common Cidex 

 mosquito seems to be the intermediate host. After being sucked into the 

 mosquito's body the larvae undergo further development and in a few 

 days are ready to infect a second person. 



The disease is known in only one locality of the United States, 

 Charleston, South Carolina, but is quite prevalent in the West Indies, 

 which lie not far from the Florida coast. Many of our service men be- 

 came infected while on duty in the South Pacific and, since the Culex 

 mosquito is so very abundant in the United States, many have expressed 

 concern that it might get started here. However, the fear seems un- 

 founded, because the larvae seem to require the particular combination of 

 heat and humidity found in the tropics in order to complete their cycle. 

 The disease requires a year or more to develop and, if discovered in its 

 early stages, the great enlargement of body parts can be prevented by 

 the injection of drugs that kill the worms. 



The Hair Worm 



A very popular superstition that has been handed down from genera- 

 tion to generation is that a horse hair, if placed in water, will turn into 

 a snake. Many a child has followed these directions and carefully 

 watched the hair for signs of life. The fact that there never has been 

 one that came to life does not seem to discourage the spread of the super- 

 stition. The hair worm, Gordius, seems to be the culprit that gave origin 

 to this idea. This worm is very slender and long, brown or black in 

 color, and does very closely resemble a long hair that might fall from a 

 horse's mane or tail. However, they are very much alive and the sight 

 of one of these worms wiggling in a puddle could easily lead to such 

 false deductions. The hair worms are parasites on aquatic insects and 

 their larvae enter the bodies of insect larvae and are later carried to other 

 ponds as the adult insect matures and flies away. 



Some Principles of Parasitology 



The term parasite has a bad connotation in the English language. We 

 frequently use it in reference to persons who attempt to go through life 

 at the expense of others. We should remember, however, that all forms 



