166 POULTRY CULTURE 



chamber is divided into two parts by the turbinated bones, 

 which are very thin and rolled like a coil of paper. 



It is probable that the sinuses of the head (infra-orbital and 

 nasal) furnish a large mucous area which warms the air to a 

 certain extent before passing into the long trachea (windpipe). 



There are certain changes that take place in the air that 

 passes into the lungs. It was seen from the above discussion 

 of air that it consisted of 20.96 volumes of oxygen, 78.00 

 volumes of nitrogen, 1.0 volume argon, and about 0.04 

 volume of carbon dioxid. 



The carbon dioxid, as shown before, is an impurity in the air. 

 It is essential to plant life, but poisonous to animal life when 

 in concentrated quantities. 



The air is spoken of as dry or saturated, depending upon 

 the amount of watery vapor it contains. 



Dry air contains about 34 of 1 per cent, watery vapor. 



When air passes into the lungs oxygen is absorbed from it 

 by the capillaries of the air tubules. In return for this there is 

 given off to the atmosphere carbon dioxid, a by-product of 

 combustion in the body. 



The volume of carbon dioxid given off is slightly less than 

 the amount of oxygen absorbed. 



Expired air is warmer than inspired air and is saturated with 

 watery vapor. 



The blood is composed of plasma, an unorganized body 

 or liquid in which floats the organized constituents of the 

 blood. In the fowl these organized bodies or cells are the red 

 blood-cells, the thrombocytes, and several types of white 

 blood-cells. 



The oxygen from the inspired air is absorbed through the 

 wet membrane, the capillary wall, into the blood-plasma, from 

 whence it is absorbed by the hemoglobin of the red blood-cells. 



The oxygen forms a loose chemical union with the hemo- 

 globin, in which form it is known as oxyhemoglobin. In this 

 form, through the blood-vessels, the cells laden with oxygen 

 are carried to all tissues of the body, where through the single- 

 layered cell capillary wall oxygen is given off to the cells of the 

 tissues through the laws of diffusion of gases, thus the oxygen 

 is enabled to support combustion in the body. A forced cessa- 



