Aug. 17, 1833.] 



• KNOWLEDGE 



97 



MAGAZINE OF SCIENCE 



PLAINLY^tfORDED-EXACTLY DESCRIBED 



LONDON : FRIDAY, AUG. 17, 1883. 



Contents op No. 94. 



A Naturalist's Tear, AEaljbit's The Shoebill {///us^raifrf) 103 



Skull. Bv Grant Allen 97 , The M orality of Happiness : Eto- 



The Chemis'trv of Cookery. XVI. lution of Conduct. By T. Foster 105 



By W. .MauieuWiUiama 98 ! Laws of Briphtnesa. VIII. By 



How to Get Stronj; 99' R, A. Proctor IPR 



Pretty Proofs of theEarth's Eotun- The Death of Captain Webb Ins 



dity. (Illua). By R. A. Proctor 100 The Face of the Sky 109 



The Amateur Electrician. Bat- : Correspondence 109 



teries. Ill 102 I Our Mathematical Column : Geome- 



Plesssnt Hours with the Microscope. j trical Problems. XII Ill 



(lUui.) ByH. J. Slack 103 I Oor Chess Column 112 



A NATURALIST'S YEAR. 



By Grant Allen. 



XIX.— A RABBIT'S SKULL. 



WALKING this sunny August morning on the breezy 

 saddle "of the great chalk down, where the combes 

 on either side are thickly overgrown with low scrub of 

 stunted juniper l)ushes,at each step I take I see the twinkling 

 white tails and tall ears of the pretty brown rabbits dis- 

 appearing into their trusty liurrows hidden cosily beneatli 

 the spreading bracken and the tangled gorse-runs. Poor 

 timid wee things, how nervously they hurry and scurry 

 away across the open patches, at the first sound of that 

 dull thud which heralds to their watchful senses the 

 approach of their heriditary foe, man, the possible hunter 

 and probable gun-bearer ! It shames mo for my kind when 

 1 think that tliey took no heed at all of yonder philosophic 

 old donkey, browzing quietly off the stemless thistles and 

 dry carline on the windy hill-side, nor of the burly liell- 

 wether himself who leads the flock of ruddled sheep in the 

 deep hollow by the old yew-tree ; but the moment they 

 heard the distant rustle of my foot-fall upon the dry 

 stems of bramble and bracken, they lifted the danger- 

 signal of their white tails forthwith to their young 

 ones among the fresh furze-brake, and darted off 

 to their holes in dismay, as from the dreaded pre- 

 sence of a familiar enemy. It has come to this, 

 tlien, that we men have waged needless war of exter- 

 mination upon all these pretty wild creatures till they 

 have learnt to condemn us all under a single cate- 

 gory — omnes uno ordine Achivos — and to shrink in- 

 stinctively even from those among us wlio would best 

 appreciate their .sympathy and their confidence. It must 

 e'en be so, though even now much may be done, with care 

 and patience, in the way of establishing friendly personal 

 relations with these, our timid fellow-denizens of the soil 

 of Britain. I will sit quiet awhile on the edg(! of the 

 disused chalkpit here till they have forgotten my sudden 

 irruption, and liy-and-by I shall no doubt be rewarded by 

 seeing them peep cautiously out from the mouths of their 

 burrows, with eyes and ears alert for every symptom of 

 danger, till at last they begin to disregard my presence, 

 and gambol freely on the open greensward before the very 

 facj of their once suspected but now unheeded visitor. 



See, here on the side of the pit is a dry, blanched skull, 

 the sole remaining memento of some lost and nameless and 

 forgotten bunny. Was he wounded by a casual gunshot, 

 and left upon the ground undiscovered, I wonder ; or was 

 he hawked at and devoured at leisure by some vigilant 

 night-prowling owl ; or was he caught on the open, and 

 miserably sucked to death by the sharp teeth of some cruel 

 weasel 1 None of these, I can see at a glance ; it was 

 Nature itself that failed my poor rabbit ; he died from 

 sheer mal-adaptation to his own ingrained racial require- 

 ments. Look closely at his lower jaw, and you will observe 

 that the great gnawing teeth — the incisors from which the 

 rodent group takes its scientific name — have grown out into 

 an immense arch, until they have doubled in again upon them- 

 selves, and at last caused the death of their unhappy owner 

 by starvation. I have seen rabliits' teeth in this same 

 condition before, and the reason for it is easy enough to 

 understand. The big incisors of rodents have no roots, 

 but spring from a permanent pulp, so that they continue 

 growing uninterruptedly throughout the entire life of the 

 animal. This arrangement has naturally been brought 

 about by survival of the fittest, because the rodents have 

 to pass their days in a perpetual round of gnawing, and 

 they can't even be happy without something or other hard 

 on which to exercise their teeth, as everybody has observed 

 in the case of tame squirrels. But in order to prevent the 

 teeth from getting entirely worn away by such continual 

 use, it is necessary that they should keep on always grow- 

 ing from below, to make up for the unceasing waste above. 

 Now, in the dead rabbit before us, the two jaws were 

 placed at a slightly irregular angle — too much underhung, 

 as the dentists call it in the human species — and therefore 

 the teeth did not meet, as they ought to do, and get worn 

 ott' at the end by attrition against one another. The con- 

 sequence has been that the incisors have bent round into a 

 perfect semi-circle, and so killed the rabbit by preventing 

 him from opening or shutting his jaws properly. 



Even in the normal state the teeth of hares and rabbits 

 are very interesting from their evolutionary implications. 

 This small group of rodents preserves for us, to some 

 slight extent, an early intermediate stage between the 

 original central mammalian stock and the thorough-going 

 modern rodents. If you look at the skull of a squirrel or 

 a mouse, or any other typical rodent, you will find that it 

 has only two kinds of teeth, incisors and molars, without 

 any canines ; and also that the incisors number two only 

 in each jaw. This is clearly a great reduction of the 

 primitive pattern, and it is accompanied by a great gap 

 between the large specialised incisors and the far smaller 

 but still somewhat peculiar molars. But if you 

 examine the upper jaw of a hare or a rabbit, 

 you will find that it contains, besides the big pair of 

 working incisors, a small rudimentary pair, immediately 

 behind them, and quite useless for any practical purpose. 

 They are, in fact, a survival from the time when the 

 ancestors of the rodents had at least four working incisors 

 in each jaw ; and they mark out the hares and rabbits as 

 being an earlier, more primitive branch of the rodent type 

 than the two-incisored rodents, like the squirrels, rats, and 

 beavers. I say at least four incisors, because we have 

 good reason to suppose that there were once six ; indeed, 

 the young hare has still six in the upper jaw at birth, Va't 

 two of them fall out while he is still a mere baby. Thir> 

 reappearance of ancestral peculiarities in very young 

 animals is, we know, one of the greatest aids to the recon- 

 struction of lost cr doubtful pedigrees. 



Fossil forms, again, often help us to piece out the scanty 

 evidence thus afforded us by living species ; and one good 

 bit of evidence in this direction is forthcoming evt u for 



