146 BLOOD AND ITS IMPORTANCE 



the different cells as the blood circulates, are dissolved in the 

 plasma and carried to the kidneys, lungs, or skin, where they are 

 thrown out. 



There are various kinds of white corpuscles. When stained, one type, the polymorphonu- 

 clear, shows nuclei with one, two, three, four, or five enlargements. In health there is a 

 definite relationship of the numbers of each of the above; in starvation or disease the fours 

 and fives are seldom found. Blood tests usually indicate the general condition of the body. 



Chemical substances in blood, known as antibodies, help to com- 

 bat germs directly, or neutralize the toxins which the bacteria 

 secrete in the blood. These substances are produced by the cells 

 during a disease or infection. Immunity to disease, which will be 

 discussed later, is brought about in the body by these antibodies. 



Blood a tissue. Red corpuscles were mentioned when tissues 

 were considered. They are five to seven hundred times as numer- 

 ous as the white corpuscles. Present investigations show that they 

 differ from other cells in that they lack a nucleus. They are made 

 from living cells located in the blood-forming tissue of the mar- 

 row of bones. Millions of these corpuscles are formed and given 

 off into the blood each minute. They are thought to gradually 

 disintegrate as they move about. The final destruction of the 

 small fragments probably takes place chiefly in the spleen and the 

 liver, but may occur in any part of the blood system. The correct 

 functioning of the red corpuscles depends upon the haemoglobin 

 which is the oxygen-carrying pigment of the blood. 



A serious decrease in the number of red corpuscles or a deficiency 

 in haemoglobin in the corpuscles causes a condition known as 

 anaemia. Certain types of anaemia in people have been treated 

 successfully by a liver diet. The liver which is used as food 

 probably contains iron gotten from destroyed corpuscles. This 

 form of iron seems to be more valuable than the iron com- 

 pounds in medicines used for treating anaemia. The body seems 



