NATURAL HISTORY". 



" Life's cares are comforts ; such by Heaven designed ; 

 lie that has none must make them or be wretched." YOUNG. 



and descending very low at the sides and behind. The white space is its ten- 

 donous portion. The lower part is muscle that contracts to draw it downward. 

 A A is the abdomen. 



88. Wliat is the liver, and how are its functions performed ? 



The liver lies horizontally on the right side of the body immediately 

 below the diaphragm, and is protected by the interior ends of the 

 lower ribs. Its function is to secrete the greenish-yellow fluid, the 

 gall or bile, which is conveyed from the liver by a canal called the 

 hepatic duct. On the lower surface of the liver is situated a small 

 pear-shaped bag, the gall bladder, which is also famished with a 

 duct, called the crystic duct, which unites with the duct from the 

 liver, and forms the common biliary duct. 



89. IVJiat is the composition of the brain ? 



The brain is composed of two substances, namely, of a grey- 

 coloured pulp, and of a wlute fibrous texture. The grey pulp is the 

 glandular or active substance, and is made up, like other glands, of 

 minute points or cavities, from which proceed the finest conducting 

 tubes. These tubes, intertwining and uniting in bundles within the 

 brain, are called the cerebral fibres, and they constitute the white 

 substance occupying, for the most part, the central and under portions 

 of the brain. The grey substance lies chiefly on and near the surface, 

 and also in the neighbourhood of those cavities within the brain, which 

 .are called its ventricles. The brain is separated by a firm membrane 

 into two distinct organs, the great brain and the small brain. The 

 great brain is situated in the front and upper part of the skull, and 

 its surface is marked by depressions and elevations which, resem- 

 bling the folds of a garment, are called its convolutions. The small 

 Drain lies und^irneath at the back of the skull ; its surface is formed 

 bv close layers of the grey substance, presenting a laminated appear- 

 ance. Four united roots or stems of the fibrous substance, two from 

 each brain, with distinct portions of the grey or glandular substance 

 u,t regular intervals interspersed, constitute the spinal cord. Nerves 

 P;ISSS 01 m of the brain and spinal cord, and are distributed to every 

 organ of the body. 



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