THE HORSE AND ITS PEDIGREE.

Oamaru Mail, Volume XXXVI, Issue 10060, 30 January 1909, Page 4 (Supplement)

THE HORSE AND ITS PEDIGREE.

j (By Dr Andrew Wilson.)

If, as a. great sciential once put it-, the p most familial' things are those wo really know very little about, despite th« wide : field they represent for observation and research, then the horse must stand forth : prominently as an illustration of the scientific opinion just quoted. The decline of the horse may be regretted for many reasons, amongst them the fact that it is the last word ill a very long and ancient history. For the animal happens to h.ive a history which is almost unique from a scientific standpoint in respect of the completeness with which its ancestry can be traced out. There are practically no links missing in the chain of evidence wluch leads us from the earliest to the latest horses, and this is the reason why in the discussion of evolution as the way of life's development, the horso has always been figured forth as a. representative example of the pedigree serving as a. proof of the origin of a species. The hoise of to-day is a much modified animal —that is, its structure has been widely altered from that of its remote ancestors, and has been metamorphosed so as to convert it into the active, fleet animal we know it to be. It is curious to note how that process of evolution, by man's aid, which we call "breeding," has in its turn produced various types of horse, ranging from the ordinaiy horse to the racer, and from the big dray-horse to the diminutive pony. This is the aftermath of evolution. Man, by careful selectio<n of parentage, can, -within limits, imitate nature's own ways and methods of evolution. But he can only work with the materials which nature provides. Probably the point which may chiefly interest us in the anatomy of the horse is the structure of its foot. The limbs of all backboned animals are constructed on the 6ame type. The arm of man, the wing of the bird, the bat's wing, the paddle of the whale, and the horse's fore-leg, all exhibit a uniformity of build. The differences are due to modifications necessary for the carrying-on of the particular mode of life selected by or impressed on each animal species. In our own arm there is an upper arm-bone, two bones in the fore-arm, eight wrist-bones, five palm-bones, and the small bones of the fingers, numbering three in each finger save in the thumb, which has only two. Xow, the fore-leg of a horse exhibits a similarity of type. There is an upper arm-bane, two "bones in the forearm —one much smaller than the other—and seven bones in its writs. But after the horse's wrist—which is popularly called its "knee"—we find one long bone, the "can- ; non bone," which is a single pain-bone, j Succeeding this are three bones, evidently . corresponding to the three in one of our , own fingers, and on the end of the last of , these three finger-bones (or "coffin bone") £ we find developed! a huge nail we call the j '"hoof." Jfow this arrangement of parts, j shows us that the horse walks an a single ( finger and toe, and this is easily identi- , fied as that corresponding to : our own s third and middle finger. But side bv 6 side with this well-developed digit we find t in the horse two slender bones attached to i the cannon-bane. These are called) "splint f bones." " They occupy the place of two c fingers—or rather, of the palin bones oor- t responding to two - digits. As the only c developed finger or toe of the horse is the i third, the splint, bones must clearly_ re- 1 present the second and' fourth fingers in a n rudimentary or, as it is better called, a 2 vestigal state. They are vestiges or t nante of fingers whicih presumably omce v figured forth in the ancient history of the s; race as fall-blown digits. This specula- t tion might be questioned, of course, alDeit 1<

i it is difficult to 6ee why nature should take the trouble of' developing useless ; splint bones at all, apart from the fact that occasionally in horses these bones give a, great deal of trouble and cause lameness. 1 Suppose we doubted the idlentity of the horse's splint-bones with its second and' » fourth fingers and toes, then it is here that the pedigree of the animal intervenes to supply the evidence of the true nature of the vestiges. Let us hie back in time- to fossil Ihorses, that come comj paratively near in point- of time to those of our own day. There is the Protohippus, first of aJJ. It shows a three-toed state. The splint-bones show forth their true nature and develop into toes. Backwards, and next in older, we have the fossil Miohippus, which walked on three toes of each foot, and possessed a vestige of a fourth toe. Still further back in time we come upon Mesohippns. It has the fourth toe better developed, and when we reach the still older Orohippus, we find an ancient horse which had four well-developed toes on its forefeet, and three toes on its hind members. We can go backward still to the Eohippus. where we find' five toes present. Now, these forms constitute an unbroken series in point of time. There are no blank§ in the array of horses, leading from the fivetoed creature of old to the one-toed : animal of to-day. It is a case, this, of direct modification of an animal towards a swifter -life, and so the horse's leg, familiar as it- is, constitutes one of the clearest proofs of evolution we con find.