He carried out these experiments at "The Bungalow", now the Navaar House in Penicuik, well before the rediscovery of Gregor Mendel's works.
Ewart crossed a male zebra with a female pony to show that the theory of telegony inherited from the Greeks was unsound.
Telegony held that a female with a history of mating with multiple males would pass on genetic qualities of all previous partners to her offspring.
Ewart later bred the mare which had produced zebra-horse hybrids with a pony, and the offspring showed no zebra qualities in either markings or temperament.
In 1883 he commissioned George Washington Browne to design a grand new house in Penicuik, finished in 1885, which is where he died on New Year's Eve 1933/34.