Anatomists’ Views of Muscles.

There is a very strict and austere custom among anatomists, which doubtless is in a measure necessary, of insisting upon following rigorously the homologies of muscles, especially in human anatomy, and in this branch of a greater subject the canons are followed to an extent that surprises the seeker after origins. A remarkable example of this is in a paper by an eminent anatomist, now Professor at King’s College, Dr. E. Barclay Smith. It is a paper on the “Morphology of the short extensor of the human fingers.”[72] He says “the precise significance of this occasional extensor brevis digitorum manus is a matter of considerable interest.” He gives four possible interpretations of this unusual muscle. The last, viz., that it is derived from a new muscle-germ alone interests us here because of the remarkable caution and austerity of his remarks on this interpreta­tion. “If an ext. brevis dig. manus cannot be regarded as an atavistic anomaly, or as a derivative from any existing musculature, the only way in which its presence can be accounted for is to suppose that it is of entirely new origin—the product of a new muscle-germ. Such an explana­tion is, of course, the last resort, and all other possible derivations must be disproved before it can be accepted.” The physiologist would probably think such an interpreta­tion was the obviously first resort. The same writer discusses at length the homology of an exceedingly rare anomaly among muscles, the extensor ossis metacarpi hallucis, and his desire on the one hand to find a missing parent for Japhet, and his honesty and accuracy on the other hand lead him to say “even when it is present, it cannot be regarded as directly atavistic, since it does not represent a normal mammalian tendency.” And he adds a gentle but remote sugges­tion—“Brooks certainly describes such a muscle in menobranchus and hatteria—two rare and remote reptiles!” But, lawful and necessary though this be, there must be stages on the path of human evolution where such a method must fail and the anatomists can do no more than hold aloof from theory or specula­tion, with a certain grim enjoyment of the disputes and difficulties of the genealogists.