reed of pigs, and weed out all the
white pigs, than the Paint Root does.

To show you how remarkably indirect may be such natural selective
agencies as I have referred to, I will conclude by noticing a case
mentioned by Mr. Darwin, and which is certainly one of the most curious
of its kind. It is that of the Humble Bee. It has been noticed that
there are a great many more humble bees in the neighbourhood of towns,
than out in the open country; and the explanation of the matter is this:
the humble bees build nests, in which they store their honey and deposit
the larvae and eggs. The field mice are amazingly fond of the honey and
larvae; therefore, wherever there are plenty of field mice, as in the
country, the humble bees are kept down; but in the neighbourhood of
towns, the number of cats which prowl about the fields eat up the field
mice, and of course the more mice they eat up the less there are to prey
upon the larvae of the bees--the cats are therefore the INDIRECT HELPERS
of the bees!* Coming back a step farther we may say that the old maids
are also indirect friends of the humble bees, and indirect enemies of
the field mice, as they keep the cats which eat up the latter! This is
an illustration somewhat beneath the dignity of the subject, perhaps,
but it occurs to me in passing, and with it I will conclude this
lecture. ([Footnote] *The humble bees, on the other hand, are direct
helpers of some plants, such as the heartsease and red clover, which are
fertilized by the visits of the bees; and they are indirect helpers of
the numerous insects which are more or less completely supported by the
heartsease and red clover.)

End of The Conditions of Existence.

A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE
ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES OF
THE PHENOMENA OF ORGANIC NATURE.

In the preceding five lectures I have endeavoured to give you an account
of those facts, and of those reasonings from facts, which form the data
upon which all theories regarding the causes of the phenomena of organic
nature must be based. And, although I have had frequent occasion to
quote Mr. Darwin--as all persons hereafter, in speaking upon these
subjects, will have occasion to quote his famous book on the "Origin of
Species,"--you must yet remember that, wherever I have quoted him,
it has not been upon theoretical points, or for statements in any way
connected with his pa