Putting to one side, for the present, the bacillus, which all pathologists agree is to be found in every leprous neoplasm, the supposed etiological factors of leprosy which have been most considered of late years, are three, viz., (I.) Heredity. (2.) A diet of fish. (3.) Contagion.
The theory of heredity has had immense support, both lay and professional, and it is curious to observe how loth some medical authors are to set themselves free from its trammels, or to question its influence in propagating the disease, even though many of the facts which they themselves adduce seem obviously to lead to quite another conclusion. As Mr. Jonathan Hutchinson points out, 1 the fact of leprosy occasionally appearing in healthy immigrants, and just as severely as if such persons belonged to leper families, is enough to prove that hereditariness goes for little or nothing in its causation. It is indeed