494 SHEEP HUSBANDRY IN THE SOUTH. 



LETTER XV. 



ANATOMY OF THE SHEEP (Continued)— DISEASES AND THEIR TREATMENT. . 



The Thoracic Viscera... The Diaphragm... The Thorax.. .The Heart, Arteries, Capillaries, and Veins... 

 The Lungs... The Windpipe, Larynx and Pharynx... The Thyroid and Parotid Glands. . .The Head and 

 its structures. ..The Brain. ..The Nc-rves. ..The Teeth. ..The Lower Extremities. ..The Bitiex Canal. .. 

 Febrile diseases — those of Europe which are not common here. . .Ophthalmia— popular remedies — proper 

 treatment. . . Pneumonia — symptoms — Mr. Spooncr's prescription for. . . Bronchitis— symptoms — treatment 

 ...Catan-h — ordinarily not dangerous— preventives. ..Malignant Epizootic Catarrh — pievalence in the 

 Northern States— character of the disease has not been understood — prevalence in author's tlock- how 

 produced— symptoms— post-mortem appenrances— character of the disease ascertained- Nosology — 

 treatment, &c. ..The Rot— its diagnosis — post-mortem appearances — description of the Fluke — causes of 

 the Rot — treatment. . .Diarrhea— cause — diagnosis — treatment. . . Dysentery — cause — dift'erence between 

 it and diarrhea — treatment.. .Garget— seat and origin of the disease — treatment. . .Nervous Diseases... 

 Apoplexy — unrecognized cases of it — several cases detailed — symptoms— treatment. ..Phrenitis. . .Tet- 

 anus... Epilepsy.. ^Rabies... Neither of them common in this country... Paralysis — symptoms — treat- 

 ment... Colic — symptoms — attributed to intussusception— true cause— treatment. 



THE THORACIC VISCERA. 



Among these, for convenience, I will include the diaphragm. 



The Diaphragm. — The diaphragm or midriff is a muscle extending en- 

 tirely across the inner cavity of the body, separating the abdomen from 

 the thorax or chest. Its structure is unique, and beautifully adapted to the 

 functions it has to perform. Its outer margin is muscular, giving it the ne- 

 cessary power of contraction, while toward the middle it changes into a 

 transparent tendonous substance. Through this tendonous substance pass 

 the oesophagus, the aorta, and the vena cava. 



If the parts of the diaphragm which immediately surround these vessels 

 had been muscular, every contraction of the former in the act of respira- 

 tion, would have compressed the latter, and therefore interfered with the 

 passage of the food to the stomach, and the circulation of the blood. In a 

 state of rest the diaphragm is convex toward the thorax. When contract- 

 ed and flattened, therefore, it enlarges the cavity of the thorax, and air 

 rushes into the lungs. Its alternate contractions and relaxations mainly 

 produce the act of respiration or breathing. 



The Thorax. — Without injuring the diaphragm, divide the sternum and 

 brisket of the sheep longitudinally through the center, with a fine saw, and 

 on pulling the lower extremity of the ribs slightly apart, the thorax will be 

 disclosed in its natural arrangement. It consists of three cavities, formed by 

 the doublings oS^\kiQ pleura, a thin serous membrane, which lines the whole 

 interior of the chest. Two outer and larger cavities (the right one being 

 the largest), contain the hmgs — a third and smaller one, lying between the 

 posterior portions of the former, contains the heart. The ossophagus pass- 

 es through the upper portion of the thorax, over the lungs and heart, and 

 between them and the spine, to the lower portion of the neck. 



The Heart, Arteries, Capillaries, and Veins. — With the size and 

 general appearance of the lieart, all are familiar. Enclosed in a mem- 

 braneous sac — the pericardium — it hangs suspended by its superior attach- 

 ments to the roof of the thorax, its lower extremity nearly reaching to its 

 floor, and pointing toward the left side. The heart has two cavities on 

 each side, termed auricles -smd, ventricles. The chyle and venous blood ai'e 



(93-1 J 



