it's proof that it existed.
it was in a Letter to the Editor written by a medical doctor offering it as a treatment to cure homosexuality! (and anyone who's been to South Beach knows how much that works)
It's proof that testosterone esters were known and available in the US in the late 1930s. It wasn't common knowledge, but it was out there. And if the knowledge was out there, why is it so hard to believe that someone would take advantage of that knowldege?
How is a single letter written to the editor of S&H the "missing link?" You're saying that the substance was not believed to influence size & strength, but rather influence one's sexual behavior.
I don't know if what existed in the late 1930's:
(1) did, in fact, increase size & strength,
(2) was KNOWN to increase size & strength,
(3) was investigated, to find out if it increased size & strength,
(4) and was available in enough quantity to be taken for that use.
And why did Ziegler need to investigate the Russian O/L team, and experiment on the York lifters if what he was looking for was right under his nose 15 years before he began his own investigation?
According to John Fair, Ziegler, Hoffman, Riecke, March, and Garcy didn't know what these pills did. They kept records, and found out that it wasn't the new training principles (isometrics), but rather the tiny pills that caused the improvements. Some might claim that York knew what the pills did, all in a plot to sell more $70 power racks.
Fair writes: "The lifting gains were obvious: that they came from steroids was not. That tiny pink pills could make you strong was still incomprehensible in the early sixties." [Page 7, Isometrics or Steroids? Exploring New Frontiers of Strenth in the Early 1960s, Journal of Sport History, Vol. 20 No. 1, Spring 1993]
If it was known in 1939, why was it not known in 1960?