130 
SURVIVAL ON LAND AND SEA 
the place covered with a thin layer of cloth. Care should be 
taken not to infect such places, as ulcers may result. 
The third group comprises the nettles and plants with stinging- 
hairs on their flowers and fruits. An examble of the latter is 
the cowhage (Fig. 45) that occurs in most tropical areas growing 
as a vine in thickets and wooded districts but not in the jungles. 
The stinging nettles are widespread but are little worse than 
those in temperate climates. There are nettle trees (Fig. 46) 
that are found in thickets, clearing and open woods. They 
should be avoided whenever possible. Treatment of irrita- 
tion caused by these plants is similar to that for the plants 
with the poisonous sap or juices. 
POLLUTED PLANT FOODS 
Far more dangerous than any of the poisonous tropical plants 
are those which — although in themselves perfectly harmless — 
carry the germs of disease. In all inhabited areas in the Tropics 
the danger of contracting disease through the eating of con- 
taminated food is ever present. Germs are left on fruits 
and vegetables when they are handled. Vegetables frequently 
are contaminated by the earth in which they are grown because 
in many countries the fields and garden plots are fertilized with 
human dung which, of course, carries the germs of the ailments 
from which the natives suffer and provides a ready source of 
reinfection. Fruits and vegetables should be eaten raw only 
when they are peeled or the outer surface is cut off with a knife 
by the person eating them. Even then care must be taken not 
to reinfect the freshly exposed portions. Vegetables and plants 
found in abandoned clearings may be contaminated from the 
