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Show 96 SIIEEP. CHAP. III. h t 1 a beautiful spiral form; from the fl·ontal bone, and t en a w. ht 1 fi·om the hca<l in the ewes they protruc1 e near ly at rw ang os ' !:> "82 l\fr· Hod(J'son · · 1 manner · o · and then become twisted m a smgulard o·I. chaffron whic·h States that the cxtraor· dm' an.' l y arc 1e nose . h 't . t'' £ · b ·ceds I. c arac ens w is so highly developed din severa\1 or~~g:he \.esuit of domcstica-of the ram alone, an apparen Y · f f t · M Bl tl tl)at the accumulatiOn o a m t. 83 I hear from r Y 1 thIOon . fat-tailed sheep of t·h e plam. s of I n dJ' a I·S rrreater in the male b , . than m• the l.r.e ma1 c '. ancLJ Fitz,i nrrer 84 remarks that the mane m o . 1 the Afn.c an mane d I.a ce I·s far more developed m the ram t mn in the ewe. · · · 1 Different races of sheep, like cattle, p~·cscnt const~tutwna dw'i'f'e r•e ncc s. Thus the improved breeds arnve at matuntyl aht a·n ·1 arre as has been well shown by Mr. Simouds throug 1 t e1r car y c- ' 1 b early average period of dentition. The scvcr~lraccs 1av~ ecome adapted to cliffcrcnt kinds of pasture and cl~mate : f~r mstanc~, 110 one can rear Leicester sheep on mountamous .rcgwns, who~~ Cheviots flourish. As Youatt has remarked, " m all the different districts of Great Britain we find various breeds of sheep beautifully adapted to the locality which they oc.cup~. No one knows their origin; they are indigenous to the s01l, chmate, pasturage, and tho locality on which they graze; they seem to have been formed for it and by it." 85 Marshall relates 86 that a flock of heavy Lincolnshire and light Norfolk shoe~ which had b?on bred together in a largo sheep-walk, part of whwh was low, nch, and moist, and another part high and dry, with benty grass, when turuod out, regularly sepm;ated from each other ; the heavy sheep drawing off to the rich soil, and the lighter sheep to their own soil ; so that " whilst there was plenty of grass the two breeds l\ pt themsel vos as distinct as rooks and pigeons." Numerous sheep from various parts of the world have boon brought during a long course of years to the Zoological Gardens of London ; but as Youatt, who attended the animals as a vete- 62 Youatt on Shoop, p. 138. 8:J 'Journal Asiat. Soc. of Bengal,' vol. xvi., 1847, pp. 1015, 1016. 84 ' Raoen des Zahmon Sohafes,' s. 77. H) • Rural Economy of Norfolk,' vol. ii. p. 136. 86 Yountt on Sheep, p. 312. On same subject, see cxoollont rcmnrks in 'Gardener's Chronicle,' 1858, p. 8~8. For experiments in crossing Cbevwt sheep with Lcicostcrs, see Youatt, P· 325. CIIAP. llf. 'l'IIEIR VARIATION. 97 rinary su.r~eon, remarks, ''few or none clio of the rot, but they are phthisical; not one of them from a torrid climate lasts out tho sccoml year, and when they die their lungs are tuberculated." 87 Even in certain parts of England it has been found impossible to keep certain Lreeds of sheep; thus on a farm on the banks of the Ouse, the Leicester sheep were so rapidly destroyed b~ pleuritis 88 that the owner couJ<.l not keep them; the coarser-slnnncd sheep never being affected. The period of gestation was formedy thought to be so unalterable a character, that ~ supposed difference between the wolf a~d th~ ~og . in this respect was esteemed a sure sign of speci~c chstJ~ctwn; but we have seen that the period is shorter m the Improved breeds of the pig, and in the larger breeds of the ox, than in other breeds of these two animals. And now we know, on the excellent authority of Hermann von Nathusius,89 that Merino and Southdown sheep, when both have long been kept under exactly the same conditions, differ in their average period of gestation, as is seen in the following Table:- Merinos .. Southdowns .. .. .. Half-bred Merinos and Southdowns -!1 bloud of Southdown Q 150·3 days. 144·2 146·3 145·5 144·2 In this graduated diffe1·ence, in these cross-bred animals havinrr different pr?portions of ~outhdown blood, we see how strict]; the two penods of gestatwn have been transmitted. N athusius remark~ tha~, ~s Southdowns grow with remarkable rapidity after birth, It IS not surprising that their frotal development s~ould ha~e been shortened. It is of course possible that the d~ff~rence m these two breeds may be due to their descent from distmct parent-species; but as the early maturity of the Southd? wns has long been carefully attended to by breedm·s, the chfference ~s more probably the result of such attention. Lastly, the fec~ndity ?f the several breeds differs much ; some generally pro~uom~ twm~ or oven triplets at a birth, of which fact the cunous Shanga1 sheep (with their truncated and rudimentary 87 Youatt on Sheep note p 491 88 'Tho V cterinary'' vol 'x .p 21.7 80 • ' • • • • A translatwn of his paper is given VOL. I. iu 'Bull. Soc. Imp. cl'Acolimat.,' tom. ix., 1862, p. 723. H |