922 THE AMERICAN NATURALIST. 
appearing in the offspring of two breeds when crossed, which 
peculiarities never appear, or appear with extreme rarity, in 
these same breeds, as long as they are precluded from crossing.” 
Lord Morton’s mare was used by Darwin in this chapter, 
not because of its telegonous young, but because its first foal, 
the hybrid, had stripes “more strongly defined and darker than 
those on the legs of the quagga.” Professor Ewart, not alone 
by his experiments upon horses and zebras, but by experiments 
upon pigeons, fowl, and rabbits, has provided an abundance of 
evidence to prove the correctness of Darwin’s views as set 
forth in this chapter, but he certainly shows that Darwin spoke 
with insufficient evidence when he said: “There can be no 
doubt that the quagga affected the character of the offspring 
subsequently begot by the black Arabian horse.” His experi- 
ments, moreover, have yielded most welcome information of a 
definite nature respecting the benign and baneful effects of in- 
breeding, the unsettled questions bearing upon sterility and the 
strange phenomena which are associated with the word “ pre- 
potency.” Both men of science and those interested in the 
practical occupation of breeding owe a debt of gratitude to 
Professor Ewart, an obligation that J. Arthur Thomson has 
acknowledged in a recent article in Natural Science, but a testi- 
monial even more fitting would be the adoption of similar lines 
of research by our numerous and amply equipped agricultural 
schools and experiment stations. The vexed problems of 
heredity never will be solved until a great many individuals 
or institutions seriously undertake experimental breeding. 
Brown University, Nov. 1, 1899. 
