P76 



PRACTICE OF AGRICULTURE. 



Past III. 



been displayed to perfect the continuance of the specie*, The tender embryo, produced by the mutual 

 Sympathies of 1 >« « 1 1 1 parent*, becomei placed to ■ situation the best adapted to its necessities and safety. 



G4I.3. Pregnancy ami evotution a/ tiefeettu. In the pregnant womb, the rudiments of the future animal 

 are covered with expansion! from the neighbouring part-; and derive nourishment from a communi. 

 Cation with the mother by meani of the umbilical cord, and farther, by a surrounding fluid. In this 

 State I speciality i- Observed in the fcetal sanguineous circulation ; the whole of its abdominal blood pass- 

 ing through it- bur >7 IS.) by which it gains a more early and perfect evolution to tit it at its first 

 entrance into life for active exertions. Under these circumstances it daily acquires increase, until the 

 distention it occasions liecnmcs too great for the capacity, when the muscular fibres of the uterus, power- 

 fully assisted by the diaphragm and abdominal muscles, contract, and thus force both the foal and the 

 membrane" into the world. 



6414 Tin- new-bom foul, on its entrance into active life, finds its organs of immediate necessity in a 

 full state of capai Ity. Unlike the infant, it is far from indigent, but can run and perform the common 

 phenomena of all animal with dexterity and case. Its powers are, however, not sufficiently developed to 

 enable it to live independent: it has therefore a necessity for seeking support from the mother, in the 

 form of milk ; and it may therefore be now considered in some measure as carnivorous. The milk is 

 derived from a bag furnished with two nipples, having excretory outlets and valves to prevent the acci- 

 dental loss of the fluid. These valves the instinct of the foal teaches it to displace by its nose. The milk 

 Of the mare being highly nutritious, its evolution rapidly increases and becomes fitted to perform all the 

 more matured functions, and when fully able to counteract its own wants, it sympathises only with itself; 

 when the parent's care being no longer necessary, the lactiferous secretion ceases. 



6415. The period o/ gestation varies in different mares : one hundred and two mares were observed by 

 Testier, of which .; foaled on the 31 Ith day, l on the :>14th, I on the 325th, 1 on the 3'Jfith, 2 on the 333d, 

 47 from the 340th to the 350th, 25 from the 350th to the 360th, 21 from the 36Uth to the 377th, and 1 on the 

 394th day ; which gives a latitude of 83 days in the time of gestation. 



Subsect. 15. The Foot. 



6416. The feet of the horse present in their united functions a series of springs with great complexity of 

 structure. An unreflecting observer considers only the horny box, and perhaps attaches as little merit to 

 it- mechanism, as he would to a well turned wooden leg of a man. But a little examination will convince 

 him that all the complexity, all the admirable mechanism displayed in the assemblage of four fingers and 

 a thumb, are here concentrated within this hnmv box and its appendages. As the parts which compose 

 the hind and the fore feet do not materially diflcr, a description of one foot will serve for the whole. 



6417. On examining a perpenitieu/ar section of the foot anil pastern (fig. 835.), there appears the coffin 

 bone (a), the navicular or nut bone {b), the coronarv or little pastern bone (c), the larger pastern 

 bone <l , the back sinew or great flexor tendon of the foot e , the same tendon sliding over the navicular 

 bone [/), its termination or insertion into the bottom of the coffin bone {g), the elastic matter of the 



sensible frog \h ), the insensible or horny frog (i), the horny sole 

 (Ar), which includes the parts of the sensible foot ; the outer wall 

 of the hoof (I), the elastic processes (ot), the attachment of the 

 extensor tendon to the coffin bone (n), and its attachment to the 

 coronarv bone (o), which completes the section. 



6418. The coffin bone {.fig 835. a) adapts itself to the form of the 

 hoof, or rather is adapted by nature to this eligible form. The 

 eminence in front receives the insertion of the tendon of the great 

 extensor muscle of the foot, whose upper attachment is to the 

 humerus or arm bone where it is fleshy, but as it passes onwards, 

 it becomes tendinous, expanding over every joint, both to prevent 

 friction, and to embrace and give attachments to each bone, by 

 which a simultaneous movement of the whole limb is made. In 



/ — " tJiajnJlfeici' -■''"' ■ ; "%^t-— e ,ho h'nder limb, this extensor and its two less adjuncts arise 



from the tibia and in part from the femur. To the sides of the 

 coffin bone are attached the lateral cartilages, and around its sur- 

 face are marks of the attachment of the laminated substance. 



6419. The coronary or small pastern bone (c), articulates with 

 the coffin at its posterior part, and articulating also with both 

 these is the navicular or nut bone (/), whose attachments to them 

 are effected by ligaments. 



6420. Tiie hoof is conical, or rather, as Clark observes, slightly truncated, and is a secretion as well from 

 the vascular parts of the foot as from the skin, as our nails are from the portion of skin called the quick. 

 The structure of the hoof is firm and fibrous ; externally plane and convex, but internally concave and 

 laminated. The quarters are the lateral parts. As the horn approaches the heels it becomes soft, and 

 is reflected inwards. The heels are parted by the horny frog {fig. 836. 6), and without the frog on each 

 side, the hoof inflects its fibres to form the bars which are seen on the under surface (fig. 836. c). In a 



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healthy foot {Jig. 837.) the heels are round, 

 wide, and smooth {a a), the frog fully ex- 

 panded (6), the bars or binders distinct (c), no 

 corns in the usual angle (rf), the sole broad 

 and concave (rfl. In a diseased foot {fig. 8370, 

 the heels are high and drawn together by con- 

 traction (a a), the frog narrow and filled with 

 fissures from contraction and thrush (b\ and 

 the sole greatly shortened in its transverse dia- 

 meter, which is morbidly counterbalanced by 

 the increased heights in the truncated form 

 (c). When the hoof is removed, the sensible 

 or fleshy sole (Jig. 835. k), above which it im- 

 mediately lies, presents itself, covering the whole of the homy sole, except so much as is taken up by the 

 sensible frog (h). This part is exquisitely sensible and vascular ; and thus we learn why injuries to it from 

 punctures produce such serious effects, and why very slight pressure from contraction of the hoof gives 

 so much pain. The sensible frog and the sensible sole form the insensible frog and sole ; but when from 

 pressure, too much moisture, or other causes, the sensible frog, instead of forming horn, secretes pus or 

 matter as in thrush, the structure of the whole becomes injured ; and the horny frog, thus losing its sup- 

 port, gradually wastes and decays. It is, therefore, evident that no thrush can be entirely harmless, as is 

 erroneously supposed. Above the sensible frog and sole is the great flexor tendon, or back sinew, insert- 

 ing itself into the vaulted arch of the coffin (fig. 835. c). This important tendon arising from its parent 

 muscle above the knee, whose origin is taken from the humerus and ulna, in its passage unites with an 

 assistant flexor, but which latter is principally distributed to the pastern bones; while the perforata, so 

 called because it is perforated by the assistant flexor tendon, is inserted into the vault of the coffin. In 

 the posterior extremities, the attachments of these two leading flexors, and a smaller lateral one, are 

 from the femtir and tibia, 

 6421. The sensible lamina:. Around the su-face of the coffin bone it has been noticed that there are 



