The other theory, that left-handedness is an inevitable accompaniment of the transposition of the viscera, is more easily tested. It is one that has been repeatedly suggested; and has not only received the sanction of Professor Hyrtl, but is supported by some undoubted cases in which the two conditions coexisted. But, as Dr. Pye-Smith remarks, “a few such instances only prove that transposition of the viscera does not _prevent_ the subject of the abnormality from being left-handed. Though attention has hitherto been little drawn to this point, there are enough cases already recorded to show that for a person with transposed viscera to be left-handed is a mere coincidence.” In confirmation of this, Dr. Pye-Smith refers to four cases, one of which came under his own observation in Guy’s Hospital, where the subjects of the abnormal disposition of the viscera had been right-handed. In the _Rochester_ (N.Y.) _Express_ of October 1877 a notice appeared of an autopsy on the body of George Vail, of Whitby, Ontario, who had recently died in the Rochester Hospital. Dr. Stone, as there stated, “noticed upon the first examination, when the patient came for treatment, that there was what is technically called ‘juxtaposition of the heart,’ which is a very rare condition. He was gratified at the autopsy to have his diagnosis confirmed, the heart being found on the right side of the body instead of the left.” I immediately wrote to Whitby, and in reply was informed that no one had ever noticed in Vail any indication of his being left-handed. A similar case of the transposition of the viscera, in which, nevertheless, the person was right-handed, recorded by M. Géry, is quoted in Cruveillier’s _Anatomie_ (i. 65). Another is given by M. Gachet, in the _Gazette des Hospitaux_, 31st August 1861; and a third in the _Pathological Transactions_, Vol. XIX. p. 147 (_Nature_, 28th April 1870). This evidence suffices to prove that there is no true relation between the transposition of the viscera and left-handedness. Dr. Struthers has shown that “as far as the viscera alone are concerned, the right side is at least 22³⁄₄ ounces heavier than the left, and that this is reduced 7³⁄₄ ounces by the influence of the contents of the stomach, leaving a clear preponderance of at least 15 ounces in favour of the right side.” The preponderance of the right side, he adds, is probably considerably greater than 15 ounces, and it is rendered still more so in the erect posture. The total weight of viscera on the right side he states at 50³⁄₄ ounces, while that of the left side is only 28 ounces, giving a visceral preponderance on the right side of 22³⁄₄ ounces. But if this relative excess of weight on the right side be the true source of right-handedness, the transposition of the viscera ought to be invariably accompanied with a corresponding change. A single example of the preponderant cause, unaccompanied by the assumed effect, is sufficient to discredit the theory.