lO ANIMALS OF LAND AND SEA 



menace to health represented by the rattlers, moccasins and 

 copper-heads of course largely offsets their value, but all the 

 non-poisonous snakes are distinctly beneficial. 



There is a widely spread behef that horses harbor in their 

 insides snakes which are occasionally expelled. These squirm- 

 ing things are not snakes, but large unjointed worms called 

 nematodes very commonly infesting horses as well as pigs and 

 other animals, and man. 



Dragon-flies eat only other insects which they catch upon 

 the wing. They do not sting horses, nor do they doctor snakes. 

 When young they live submerged in streams and ponds eating 

 insects as they do when fully grown. Sometimes the larvae of 

 the large ones eat small fish, but not unless severely pressed by 

 hunger. In this country they are termed the "devil's darning 

 needles" and with this name comes the idea that they can sew. 



Some bees that Willie thought he saw on a dead animal were 

 not bees at all, but bee-flies, the young of which sometimes 

 live in carcasses. In ancient times it was supposed that bees 

 were formed spontaneously from dead animals, these flies being 

 mistaken for the honey bees. No living things of any sort 

 ever appear spontaneously. All living things are the child- 

 ren of similar living things. All flies for instance, arise from 

 maggots which come out of eggs laid by parent flies. All cases 

 of malaria or of typhoid arise through transfer of the "germs" 

 from other cases. This rule has no exceptions. 



In the country you will sometimes hear that bumble-bees 

 eat honey bees, and even wasps. The bumble-bees do no 

 such thing; but there is a large asilid fly, very stout and 

 colored like a bumble-bee, which has this habit. 



These few examples serve to illustrate some common mis- 

 conceptions, out of hundreds. A few of these are curious and 

 harmful. In parts of Europe it is thought that to be healthy 

 one must harbor cooties. The logic is that when one dies 

 his cooties leave him; therefore cooties must be a sign of 

 health. Now cooties carry typhus fever and are the cause of 

 other sicknesses as well. But when a man believes his health 

 depends on having cooties, what can a doctor do? 



