D. Dewar, however, states (_Birds of the Plains_, p. 42) that the coloured peahens in the Zoological Gardens at Lahore show a decided preference for the white cocks, which are kept in the aviary along with normally coloured cocks. He gives it as his opinion that “the hens select the white cocks, not because they are white, but because of the strength of the sexual instincts of these latter. The white cocks continually show off before the hens; the sexual desire is developed more highly in them than in the ordinary cocks, and it is this that attracts the hens.” Pearson’s Investigations The only zoologists who have investigated experimentally the question of sexual selection appear to be Karl Pearson and Frank Finn. The former tried to determine, by actual measurements, whether there is any preferential mating among human beings as regards physical characteristics. “Our statistics,” he writes, on page 427 of _The Grammar of Science_, “run to only a few hundreds, and were not collected _ad hoc_. Still, as far as they go, they show no evidence of preferential mating in mankind on the basis of stature, or of any character _very_ closely correlated with stature. Men do not appear, for example, to select tall women for their wives, nor do they refuse to mate with very tall or very short women.” As regards eye-colour, Pearson seems to have arrived at somewhat more definite results. “We conclude,” he writes (p. 428), “that in mankind there certainly exists a preferential mating in the matter of eye-colour, or of some closely allied character in the male; in the case of the female there also appears to be some change of type due to preferential mating. . . . The general tendency is for lighter-eyed to mate, the darker-eyed being relatively less frequently mated.” But Pearson’s experiments seem to show that as regards stature and eye-colour there is “a quite sensible tendency of like to mate with like.” “In fact,” writes Pearson, “husband and wife for one of these characters are more alike than uncle and niece, and for the other more alike than first cousins.” He adds, “Such a degree of resemblance in two mates, which we reasonably assume to be not peculiar to man, could not fail to be of weight if all the stages between like and unlike were destroyed by differential selection.”