s by selective affinity from the
blood those materials which are necessary for its sustenance, we must
not forget that each organ draws at the same time by a similar selective
affinity the specific odorous substances requisite for its constructive
requirements.

We have now only to suppose that the embryonal germ contains, like the
blood itself, all the odorous substances pertaining to the various
tissues and organs of the parent, and we shall understand which is the
moving principle in the germ that evolves an offspring, shaped in the
image and after the likeness of the parents.

In plants it is the blossom which is entrusted with the function of
reproduction, and the odorous emanations accompanying that process are
well known. There is strong reason to believe that something similar
prevails in the case of animals, as may be seen from an examination of
what embryologists call the aura seminalis.

Let us now inquire what the effects are of odours generated in the outer
world on animals. The odorous impressions produced may be pleasant or
unpleasant, pleasant to one and unpleasant to another animal. What is
it that constitutes this sensation of pleasure or displeasure?
Professor Yaeger answers, It is harmony or disharmony which makes all
the difference. The olfactory organs of each animal are impregnated by
its own specific scent. Whenever the odorous waves of a substance
harmonize in their vibration with the odorous waves emanating from the
animal; in other words, whenever they fall in and agree with each
other, an agreeable sensation is produced; whenever the reverse takes
places, the sensation is disagreeable. In this way it is that the odour
regulates the choice of the food on the part of the animal. In a
similar way the sympathies and antipathies between the various animals
are regulated. For every individual has not only its specific but also
its individual scent. The selection between the sexes, or what, in the
case of the human race, is called love, has its mainspring in the
odorous harmony subsisting in the two individuals concerned.

This individual scent--a variation of the specific odorous type--alters
(within the limits of its speciality) with age, with the particular mode
of occupation, with the sex, with certain physiological conditions and
functions during life, with the state of health, and last, but not
least, with the state of our mind.

It is to be remembered that every time protoplasm