The first formula was only an abstract general statement of what is common to all cases of maximum sexual attraction so far as the sexual relation is governed by the law. I must now try to find an expression for the strength of the sexual affinity in any conceivable case, an expression which on account of its general form, can be used to describe the relationship between any two living beings, even if these belong to different species or to the same sex.
If
χ {
α Mα´ W
and
γ {
β Wβ´ M
| χ | { | α M | and | γ | { | β W |
| α´ W | β´ M |
(where α, α´, β, and β´ are each greater than 0 and less than unity) define the sexual constitutions of any two living beings between which there is an attraction, then the strength of the attraction may be expressed thus:
A = Kα - β f t