300 THE SNAKES OF SOUTH AFRICA. 
thus benumbed, and rendered incapable of killing off disease 
microbes, which multiply and cause a disease peculiar to their 
species or kind. If you disregard the laws of eating and drinking 
then you should not blame Providence if the machinery of your 
body gets out of gear, and disease microbes attack it. 
How To KEEP YouR BLooD PURE. 
The first essential is to breathe plenty of oxygen, and inhale 
deeply. A great many people get into the habit of breathing 
in a very shallow way, inflat- 
ing only a portion of their 
lungs. Boys and girls who 
have flat chests should be 
compelled to take systematic 
club, dumb-bell, or other suit- 
able physical exercises for en- 
larging the chest and lung 
capacity. The exercises should 
not be discontinued until the 
chest becomes convex. 
Practise deep breathing 
until it becomes a habit. Sit 
in a chair with a straight back, 
bolt upright. Slowly breathe 
as much air into your lungs as 
you are able to force down. 
Retain it till you count five, 
then slowly exhale it. Con- 
tinue this for fifteen minutes, 
twice a day if possible. At 
first you will feel a_ trifle 
Fic. 125. Rough diagram showing how the giddy with the unaccustomed 
blood circulates through the body. Poison- gqmount of oxygen which gets : 
laden blood runs to the heart from all 5 A 
over the body. Itis then pumped into jnto your blood, but this soon 
the lungs and purified by the air we 
breathe. It returnsto the heart to be wears off. Breathe through 
again pumped to the remotest corners of "i ; 
the body. (From Blackie’s Physiology.) your nose. It is a microbe 
and dust filter, and warms the air also. 
