Silver Dart would revert to Baldwin and McCurdy, who began the Canadian Aerodrome Company and would later demonstrate the aircraft to the Canadian Army. Heredity and genetics Bell, along with many members of the scientific community at the time, took an interest in the popular science of heredity which grew out of the publication of Charles Darwin's book On the Origin of Species in 1859. On his estate in Nova Scotia, Bell conducted meticulously recorded breeding experiments with rams and ewes. Over the course of more than 30 years, Bell sought to produce a breed of sheep with multiple nipples that would bear twins. He specifically wanted to see if selective breeding could produce sheep with four functional nipples with enough milk for twin lambs. This interest in animal breeding caught the attention of scientists focused on the study of heredity and genetics in humans. In November 1883, Bell presented a paper at a meeting of the National Academy of Sciences titled "Upon the Formation of a Deaf Variety of the Human Race". The paper is a compilation of data on the hereditary aspects of deafness. Bell's research indicated that a hereditary tendency toward deafness, as indicated by the possession of deaf relatives, was an important element in determining the production of deaf offspring. He noted that the proportion of deaf children born to deaf parents was many times greater than the proportion of deaf children born to the general population. In the paper, Bell delved into social commentary and discussed hypothetical public policies to bring an end to deafness. He also criticized educational practices that segregated deaf children rather than integrated them fulling into mainstream classrooms. The paper did not propose sterilization of deaf people or prohibition on intermarriage, noting that "We cannot dictate to men and women whom they should marry and natural selection no longer influences mankind to any great extent." A review of Bell's "Memoir upon the Formation of a Deaf Variety of the Human Race" appearing in an 1885 issue of the "American Annals of the Deaf and Dumb" states that "Dr. Bell does not advocate legislative interference with the marriages of the deaf for several reasons one of which is that the results of such marriages have not yet been sufficiently investigated." The article goes on to say that "the editorial remarks based thereon did injustice to the author." The paper's author concludes by