TROPICAL FORESTS 
77 
In some areas there are crocodiles in the streams. They can 
be avoided by not going into the water, or, when it is necessary 
to cross larger rivers, by doing so on improvised rafts. Authen- 
tic cases of crocodiles attacking human beings are practically 
impossible to find, so you don’t need to worry over that. If 
you should approach or attempt to kill one along the shore, 
however, be careful of the sweep of its tail. They can move 
very swiftly, and the powerful tail is strong enough to break a 
man’s leg. 
Some of the South American streams have fish called caribe, 
palometa, or piranha that will attack men or animals entering 
the water and inflict dangerous wounds. They are infuri- 
ated by blood or sores but often do not attack persons without 
these conditions. They, too, can be avoided by staying out of 
streams where natives say they occur and by crossing on rafts. 
Blood Worms 
It is advisable to stay out of fresh water, as far as possible, in 
certain areas because the lakes, rivers, streams, swamps, ponds, 
irrigation ditches, and flooded rice fields may contain the young 
forms of various blood-worms or flukes. They may enter the 
body through the skin of bathers or persons wading in such 
waters, or through contaminated drinking water that has not 
been boiled or sufficiently treated with chlorine. The young 
forms of these flukes are harbored by certain kinds of fresh- 
water snails. When they leave the snail and are discharged into 
the water they die within 48 hours unless another suitable vic- 
tim is found. Hence water that has been stored in a container 
that is free of snails will be safe for washing and bathing in from 
570603° — 44 Q 
