The head is represented by a straight line because it
presented (apparently) no variation. The body is next given, the
specimens being arranged in the order of their size from No. 1, the
smallest, to No. 14, the largest, the actual lengths being laid down
from a base line at a suitable distance below, in this case two inches
below the centre, the mean length of the body of the fourteen specimens
being two inches. The respective lengths of the neck, legs, and toe of
each specimen are then laid down in the same manner at convenient
distances apart for comparison; and we see that their variations bear no
definite relation to those of the body, and not much to those of each
other. With the exception of No. 5, in which all the parts agree in
being large, there is a marked independence of each part, shown by the
lines often curving in opposite directions; which proves that in those
specimens one part is large while the other is small. The actual amount
of the variation is very great, ranging from one-sixth of the mean
length in the neck to considerably more than a fourth in the hind leg,
and this among only fourteen examples which happen to be in a particular
museum.
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