me in making this
religious lady understand the existence of so near a kinswoman, and take
her under her protection.--Thus strangely did Father Francesco find
himself again obliged to take up that enchanted thread which had led him
into labyrinths so fatal to his peace.

* * * * *

METHODS OF STUDY IN NATURAL HISTORY.

V.

It is in the search after the true boundaries and characteristics of
orders that we may expect the greatest advance by the naturalists of the
present day; and yet there is now much discrepancy among them, some
mistaking orders for classes, others raising families to the dignity of
orders. This want of agreement in their results is not strange, however;
for the recognition of orders is indeed exceedingly difficult. If they
are, as I have defined them, groups in Nature founded upon a greater or
less complication of structure, they must of course form a regular
gradation within the limits of their class, since comparative perfection
implies comparative rank, and a correct estimate of these degrees of
complication requires an intimate and extensive knowledge of structure
throughout the class. There would seem to be an arbitrary element
here,--that of our individual appreciation of structural character. If
one man holds a certain kind of structural characters superior to
another, he will establish the rank of the order upon that feature,
while some other naturalist, appreciating a different point of the
structure more highly, will make that the test character of the group.
Let us see whether we can eliminate this arbitrary element in our
estimate of these groups, and find any mode of determining orders that
shall be unquestionable, and give us results as positive as a chemical
analysis according to quantitative elements. I believe that there are
such absolute tests of structural relations. It is my conviction, that
orders, like all the other groups of the Animal Kingdom, have a positive
existence in Nature with definite limits, that no arbitrary element
should enter into any part of our classifications, and that we have
already the key by which to solve this question about orders.

To illustrate this statement, I must return to the class of Insects. We
have seen that they are divided into three orders: the long cylindrical
Centipedes, with the body divided throughout in uniform rings, like the
Worms; the Spiders, with the body divided into two regions; and the
W