, and all such twins are found
invariably to be of the same sex. The consequence of this is, that I
find a curious discontinuity in my results. One would have expected
that twins would commonly be found to possess a certain average
likeness to one another; that a few would greatly exceed that
average likeness, and a few would greatly fall short of it. But this
is not at all the case. Extreme similarity and extreme dissimilarity
between twins of the same sex are nearly as common as moderate
resemblance. When the twins are a boy and a girl, they are never
closely alike; in fact, their origin is never due to the development
of two germinal spots in the same ovum.

I received about eighty returns of cases of close similarity,
thirty-five of which entered into many instructive details. In a few
of these not a single point of difference could be specified. In the
remainder, the colour of the hair and eyes were almost always
identical; the height, weight, and strength were nearly so.
Nevertheless, I have a few cases of a notable difference in height,
weight, and strength, although the resemblance was otherwise very
near. The manner and personal address of the thirty-five pairs of
twins are usually described as very similar, but accompanied by a
slight difference of expression, familiar to near relatives, though
unperceived by strangers. The intonation of the voice when speaking
is commonly the same, but it frequently happens that the twins sing
in different keys. Most singularly, the one point in which
similarity is rare is the handwriting. I cannot account for this,
considering how strongly handwriting runs in families, but I am sure
of the fact. I have only one case in which nobody, not even the twins
themselves, could distinguish their own notes of lectures, etc.;
barely two or three in which the handwriting was undistinguishable
by others, and only a few in which it was described as closely alike.
On the other hand, I have many in which it is stated to be unlike,
and some in which it is alluded to as the only point of difference.
It would appear that the handwriting is a very delicate test of
difference in organisation--a conclusion which I commend to the
notice of enthusiasts in the art of discovering character by the
handwriting.

One of my inquiries was for anecdotes regarding mistakes made
between the twins by their near relatives. The replies are numerous,
but not very varied in character. When the twins are childr