OCR Text |
Show 124: DOMESTIC .RABBITS. Ci!Ar. IV. become modified under ·domestication. No one will say, for instance, that the oceipital foramen, or the atlas, or the third cervical vertebra is a part of slight importance. If the several vertebrro of the wild and lop-eared rabbits, of which :figures have been giv n, had been fonnd fossil, pal::contologists would have declared withont hesitation that they bad belonged to distinct species. The r!fects qf the use and clis11se qf pr.~1·ts. -In tho largo lop-oared rabbits the relative proportional lengths of tbo bones of tho same Jog, and of tho front and hind legs compared with each other, have rcmainccl nearly the same as in tho wild rabbit; but in weight, the bones of tho hind logs apparently have not increased in duo proportion with the front legs. 'rho weight of the whole body in the largo rabbits examined by mo was from twice to twice and a half as great as that of tho wild rabuit; and tho weight of tho Mncs of the front and hind limbs taken together (excluding the feet, on account of tho difficulty of p01·fcctly cleaning so many small bones) hn.s increased in the large lop-cared rabbits in nearly tho same proportion; consequently in due proportion to tho weight of body which they have to support. If wo take tho length of tho body as tho Rtandar l of comparison, tho limbs of tho largo rn.bbits have not increased in length in duo proportion by one inch, or by one inch and a half. Agn.in, if wo take as tho standard of comparison tho length of tho skull, which, as we have before soon, ha.s not increased in length in duo proportion to tho length of body, the limbs will be found to be, proportionally with those of tho wild rabbit, from half to three-quarters of an inch too short. llcnco, whatever standard of comparison bo taken, tho limb-bones of the largo lop-cared rabbits have not increased in length, though they have in weight, in full proportion to tho other parts of tho fmmc; and this, I presume, may bo accounted for by tho inactive lifo which dll'ing many generations they have spent. Nor haS tho scapula increased in length in due proportion to the increased length of the body. The capacity of the osseous case of the brain is a more interesting point, to which I was led to attend by finding, as previously stated, that with all domesticated rabbits the length of tl1e skull relatively to its breadth has greatly increased in comparison with that of tho wild rabbit. If we had posse sed a largo number of domesticated rabbits of nearly the same size with the wild rabbit, it would have boon a simple task to have measured and compared tho capacities of their skulls. But this is not the case; almost all tho domestic broods have larger bodies than wild rabbits, n.nd tho lop-cared kinds arc more than double their weight. As a small animal has to exert its senses, intellect, and instincts equally with a large animal, we 011ght not by any means to expect an animal twice or thrice as largo as another to have a brain of double or treble tho sizc.27 Now, after weighing !)'~ See Prof. Owen's remarks on this subject iu his papet on tho ' Zoological Significance of tho Bmiu, &c., of Man, &c.,' read before Brit. As~ociation, 1862; with rc::;pcd to Bird::;, see 'Proo. zjoolog. Soc.,' J an. 11th, 1 ~HS, p. 8. CHAP. IV. EFFECTS OF USE AND DISUSE. 125 rtahbob ibt<o;d ieI sf ionfdf ~ ~1:. twi' Jd rabbi.t s, and of foUl' largo but not fattenecl lop-earocl 1 to 2·l7. . a on an average tho wild arc to tho lop-cared in weight ' m average length of body as 1 to 1·41 · hil · . · as (moasmcd as hereafter to be described) tllOy ar~ ~:l s! m capa~Ity of skull we sec that tho capacity of the s,r·uJ l l Y s 1 to 115. llonco b · h • ~ · ' anc consequently th · ram, as increased but little . l t· l t . o Slzo of the ~nd this fact explains tho na;.r~~~;se :r ~h;h~ J~r~asc~ size of ~he body; m all domestic rabbits. s u relatively to 1ts length In tho upper half of the following table I h . of tho skulls of ton wild .rabbits; and in tho 1 av_e gi~cn tho IDOl.j<suromcnts domesticated kinds. As these l'ab,u·i ' ts. c1u :Ju:I.'c ro wsoe rg rheaaltf! of· e lev· en t·h oroughly sary to have some standard by w.bJ. c1 t ' Y m Size, It is nccos- I o compare th · · skulls. I have selected tho length of l· 11 ' 0 capamt10s of their tho larger mbbits it has not, as already ;~~~d ~s t~e bes.t standard, for in ~s the body; but as the skull, lilrc ever other' IDClcas~d ~length so much It nor any other part affords a perfect ~tandarf.art, val'los m length, neither In the fir:;t column of figmes the oxtrcm inches and decimals. I am aware that t~ l~ngth of tho skull is given in greater accuracy than is possible. but I ha~so£ mcas~rcmcntc;; pretend to record the exact length which the 0 ound It tho least trouble to columns give tho length and "'voight ~~~p~c;;s gave. Tho second and third have been made The fomth col . o y, whenever these measurements weight of small. shot with which u:~ ~~vc~l tl~e ~aEacity of the skull by tbc pretended that these weights are accu:t~c;; w~thince: filled; ~ut it is not fifth col~n tho c~pacity is given which tho skul f~w grams. In tho calculation, according to tho len th of . 1 ought. to have had by the wild rabbit No. 1; in tho ~th co~~ull, m co~pal'lson with that of actual and calculated capacities a d . ~ tho cliffercnce between the increase or decrease arc gi·ven ' F~ n . mt e seventh the percentage of ' · ·or ms ance as tJ 'ld has a shorter and lighter body than tho wild .' . 1e WI rab?it No. 5 expected that its skull would have h d l mbbit No. 1, we might have as expressed by tho weight of shot i: 87~ss ~a?acity;. the. actual capacity, than that of tho fu·st mbbit B t ~rams, which IS 97 grains le ·s length of then: skulls we sec that .u ;o~~~·mg thc.so two. rabbits by the and in No. 5 2·96 m· 'chos m· I ' gtmh o. ~skull Js 3·15 mchcs in lcngih en · according· t th · · ' No. 5 ought to have bad a capacit' f 91 . o IS ratio, tho brain of tho actual capacity but only by 38 Y o. 3 Ograms of shot, which is above ( · ' grams. r to put th · wa~ as m column vu), the brain of this small '. . o case m another grams of weight is only 4 per cent too li ht mbbi~, ~o. 5, for every 100 to tho standard rabbit .No 1 to h g ,-that JS, It ought, according taken the mbbit No. 1 as the ~tanda~~ o~con 4: p~r cont. heavim·. I have having a full average length thi h comparJSon because, of tho skulls tho. le~st favourable to the r·o~ult ~hi~~ ih~i;~ast capacity; so that it is bram m all long-domesticated rabbits h . to ~ho':' na~cly, that the or l:olativcly to the length of tho h d a ~cicase~ m Slzc, CI~hcr actually, bmm of tho wild rabbit H d I ~1 an bod~, m companson with tho standard, the following rc~nlts ~voulda~cn t~o Insh rabbit, No.3, as tho Turning to tho Table : tho fu· . a~e .con som?what more striking. same length, and those differ bu:\ii~~:r . wild ~·a? bits J;avc skulls of the e m capa.mty. 1hc Sandon rabbit |