MUSCULAR SYSTEM 295 
they form. They are very minute. Each living and growing cell 
is made up of a cell wall containing a mass of protoplasm with its 
nucleus, cell sap, and other cell contents. Protoplasm resembles 
the white of an egg, but may be jellylike in consistency. Living 
cells grow and multiply in large numbers together. Those of one 
kind or structure are united to form a certain kind of tissue. 
There are six kinds of tissues recognized in the body: (1) 
Muscular tissue; (2) epithelial tissue, or skin; (3) nervous tissue; 
(4) connective tissue, which surrounds other tissues and organs, 
holding them in place; (5) bony tissue; (6) fatty tissue. 
In order to accomplish a definite purpose and to work to the 
best advantage, several kinds of tissues are usually associated 
together to form organs. For example, the heart is a group of 
different tissues working for 4 definite purpose. Each organ has 
a work to perform, which is closely associated with other organs 
working in codperation with it. Such a combination is called a 
system. The following systems make up the working parts of 
the fowl’s body: Muscular, digestive, circulatory, respiratory, 
reproductive, and nervous systems. The nervous system, and 
others of minor importance to the poultryman, will not be dis- 
cussed _ here. 
Muscular System.—The muscular system has a double func- 
tion to perform in the case of the fowl: (1) To furnish the means 
by which the bird can move, (2) to cover the bones and fill out 
the body contour. This latter function tends to give the show 
bird the highest degree of type and perfection of bodily propor- 
tions and the standard shape. 
The character and extent to which the muscular tissue has 
been developed determine in a large measure the value of the bird 
for table purposes. The character and form of muscles in any 
breed are largely inherited, but they can be influenced by feeding 
and management. For example, the effect of close confinement 
compared with liberal exercise on the structure of the muscular 
tissue is easily shown. The former will produce soft flesh, fine in 
texture, and relatively free from connective tissue; the latter will 
produce less flesh, coarse in structure, with an increased amount 
of connective tissue. . 
Muscles vary greatly in size and thickness in different parts of 
the body. Those of most importance, from a commercial stand- 
point, are found chiefly on the breast and limbs. The former are 
the muscles which control flight. 
