98 PRACTICE OF AGRICULTURE. Part III. 



doracsticated than in those which run wild. An animal will lose one fifteenth before he dies. A horse 

 lost forty-four pounds without apparent injury. Probably the quantity contained in the body may vary 

 according to eireomstances : between one eighth and one tenth of the whole mass is a fair metlium. 



63.')\, The pulse. From the contraction of the heart ami cMisequent dilatation of the arteries to receive 

 the blood, and jiass it onward to all' parts of the body, which is called the diastole ; so a dilatation of the 

 heart and cotitraction of the arteries necessarily occurs, which is called the systole ; and these two causes 

 operating alternately produce the phenomena of circulation. The momentary increase in capacity in the 

 diameter of the artery is called \.\\e pulse. As there is seldom disease present, without some alteration in 

 the circulation also, so the pulse is attended to as an indication of health or disease. The circulation being 

 carried on over the whole body, the pulse may be felt universally ; but some situations are more favourable 

 than others ; as the heart itself, the pasterns, at the root of the ear, &c. : but the most convenient of all 

 is at the branch of the posterior jaw, where the maxillary artery may be readily detected {fig. 833. t). 

 The natural pulse in the horse is about 45 beats in a minute ; in the ox the same; in man 75; in the 

 dog 90. When^ the piitse is much accelerated, the circulation is accelerated also. If, with its quickness, 

 fulness of vessels and hardness are apparent, the circulaticm is morbidly hurried, and iuflammation general 

 or partial is present 



SuBSECT. S. Absorbents of the Horse, ''.'''l^y'^ ^' ' 

 &^2~The absorbent Sjis^m is a very extraordinary and a very important one ; ftr if the Uood builds up 

 and repairs parts, tlie absorbents pwU down, remove, and take them away aga-i-n. , They ase composed of 

 the lymphatics and iacieals. Both kinds, although thin and transparent, are strong, and appear to have a 

 contractile power : where very minute they are called capillaries. The lacteal absorbents are situatetl in 

 the mesentery and intestines, whence they draw the chyle, or nutritious fluid by which the blood is 

 nourished and augmented. The chyle is carried forward from the mesentery into a tube called the tho^-acic 

 duct, which, passing up by the side of the a6rta, pours its contents into the heart through the medium of 

 the jugular vein. The lymphatic absorbents differ from the latter only in being situated over the whole 

 body, and being the retiipients of the various matters of the body; whereas the lacteals api)ear to absorb 

 tlve cliyle only. From numerous facts, we know that the various organs are continually suffering a 

 destruction and a removal of parts, and that what the absorbents take away, the arteries renew ; and to 

 this constant change, most of ti>e alterations of the body are to be attributed with regard to the structure 

 of i>arts. We use our powei^bver these vessels in the horse medicinally. We stimulate the absorbents to 

 take up diseased solutions of fluids from various parts of the body, as in watery swellings in the legs by 

 mercury and by friction, or by pressureili the way of bandage. When deposits are made of hard matter, 

 or ligament or bopCj we sthnulate them by blistering or by firing. It is by stimulating the absorbents 

 that splints and spavins are removed. Exercisers a very powerful stimulus to absorbents; thus it is that 

 swelled legs are removed by hatf an hour's exercise. In the horse, the lymphatics are more liable to 

 disease than the lacteals, but in man the reverse. Farcy diseases the lymphatics irreparably. 



SuBSECT. 4. Nerves and Glands of the Horse. 



63 )3. The nervous system of the horse is composed of white medullary cords, springing fVom the brain and 

 spinal marrow, whence they aregenerally distinguished into the cerebral and spinal nerves : the internal 

 structure of these bodies is' fibrous, and their ramifications extend to evety part of the body; it is sup- 

 |K)sed that the brain is the seat of sensation and vohtion, and tiiat the nerves are only the messengers of 

 it. The sensibility of a part is usually proportioned to the number and size of its nerves ; nervous 

 influence occasions motion. Ffom some cause, unknown to us, some motions are voluntary, and some 

 involuntary ; but both are brought about by nervous agency. As the nerves are the media of sensation ; 

 fo a division of their cords has lately been attempted, with success, to relieve certain painful affections ; 

 the most prominent instance is, in the division of the pastern nerves for the relief of the painful affection 

 of founder. Tetanus, or locked jaw. Which seems a morbid irritation on the nerves, has been recom- 

 mended to be treated in the same way. 



6354. The cerebral nerves, arising in pairs immediately from the brain, are the olfactory, optic, motures 

 /)cu!i, path^tici, trigcmini, abducents, auditory, lingual, par vagum, and the pair called the intercostal or 

 great sympathetic, from its extensive connection. 



635.5. The spinal nerves are those which arise immediately from the spinal marrow, as the cervicals, hu- 

 merals, ulnar, metacarpal, and pastern nerves ; the dorsal, the lumbar, crural, sciatic, popliteal, sacral, 

 and the nerves to the posterior extremities, which correspond with those of the anterior. 



6 ).56. The glands are numerous, and placed in every part of the boiiy ; they may be characterised as se- 

 cretory bodies, composed of all the different vessels enclosed in a membrane ; their office appears to be to 

 secrete or form some fluid, as the liver secretes bile, and the kidney urine. They are classed into follicu- 

 lose, globate, glomerate, and conglomerate ; they also receive specific names according to their situations, 

 or according to the fluid they secrete, as lachrymal, salivary, etc. 



SuBSECT. p. Integuments of the Horse's Body. 



6357. The common integuments may be considered as the hair, the cuticle, the epidermis, or insensible 

 or outer skin, the rete mucosum, which is immediately under this, the ctitis, sensible or true skin, the 

 cellular membranes, which contain fat and other fluids, and the panniculus carnbsus or fleshy pannicle ; 

 to these may be added, the imguisj nails or hoofs, which we shall describe separately. 



6358. Hair is the clothing of brutes, and hence is very important to them, and as it enters largely into 

 the arts, it is also important to us. (1851.) It appears to be a production of the true skin, arising from a 

 bulbous end, which penetrates the rete and cuticle in the form of an elongated cone. In some parts hairs 

 appear singly, as about the muzzle ; in others in masses, as on the mane, tail, and over the body generally, 

 as an inclined congregated mass ; hair varies in colour, and therefore appears by nature intended both for 

 ornament and use. 



6359. The cuticle is situated immediately under the hair (1845.), and appears a hard insensible covering, 

 purposely placed to guard or defend the sensible skin underneath. The cuticle lines many of the large 

 openings of the body^ as the mouth, whence it is continued into the stomach, lining one half of it. It is 

 perforated by innumerable small vessels that give out and take in various matters ; through these blisters 

 act on the true skin, inflame it, and force it to secrete a quantity of fluid, which thus pushes the cuticle 

 from the cutis. It exists before birth, and is speedily renewed after birth, when accidentally destroyed, 

 arid, like the true skin, thickens by pressure; it is constantly undergoing changes; it exfoliates in the 

 form of powder, or little scales, over every part of the body, and is that substance called dandriff^ which 

 grooms are so careful to remove with the currycomb. 



6360. The rite mucosum is a mucilaginous substance placed like a net between layers of cuticle and 

 cutis ; and although very universal in animated nature, its use is unknown. 



6361. The cutis, chrium, or true skin. (1847.) This very general investure of the body is situated im- 

 mediately under the two former ; it is very vascular, and is furnished with innumerable small villous 

 processes of exquisite sensibility, and which, without doubt, were intencJetl to constitute it as the real 

 organ of touch. It is much thickened by pressure ; asses, from the beatings they are subjected to, have 

 it of immense thickness on the rump. It naturally also exists in various degrees of density according 

 to the wants of the animal. Like the cuticle it is perforated by numerous openings which correspond 

 with those of the latter membrane. Its composition appears principally gelatine, and hence it is em- 

 ployed in the manufacture of glue ; its gelatine uniting with the matter called tannin, becomes insoluble 



