QUESTIONS 
465 
SUMMARY 
All living things breathe oxygen which, in man and the 
higher animals, is carried by the blood to the cells of the body. 
The parts which man uses in breathing are more highly 
developed than in any other animal. Man has a voice box, 
the larynx, by means of which he is able to make a wide 
variety of sounds. The blood of man is similar to the blood 
of all other vertebrates, although not identical. It consists 
of red and white corpuscles which move freely in the plasma. 
The blood is confined in the blood vessels through which it 
is forced by the heart. Excretion includes the waste products 
derived from the living protoplasm. The lungs, the sweat 
glands of the skin, and the kidneys remove this waste from 
the blood. The care of waste requires that we give increas¬ 
ing attention to the question of sewage and water supply. 
QUESTIONS 
Compare the respiration of man, the hydra, and the earthworm. 
Compare the lungs of man with the gills of a fish. What is blood? 
What are its uses ? What is the difference between veins and arteries ? 
Explain the work of the skin and kidneys. What is sewage? How 
is it cared for in your home? city? town? Where do you get your 
water supply ? 
