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In 1849, a man by the name of Arnold Berthold followed suit with John Hunter's previous experiments and made some new discoveries of his own.
Arnold castrated roosters as well but this time, he returned a testicle back into the body cavity of the corresponding castrated rooster. This led to the rooster showing normal sexual behavior and comb development. As a conclusion, the result was that the testes must have released something into the blood of the rooster. Now today, as we know, the consequence that was seen through this experiment was the responsibility of hormones.