San Quentin Chief Surgeon Leo Stanley ... was experimenting with putting animal testicles into men, but human-to-human transplants were preferred. Working at San Quentin gave him access to the organs of recently dead young men at a rate few other doctors could boast. In the next 20 years, he would perform over 10,000 testicular implants within the walls of San Quentin State Prison. Upon arriving, Stanley remarked later, he was upset by the lack of racial segregation among the inmates. Whites, Negroes, and Indians commingled here indiscriminately," he complained. A lifelong eugenicist " a belief he continued to hold well past Nazi horrors being revealed " Stanley set about making changes immediately. Before he hit on gland implants, his favorite fix was sterilization. In 1909, California passed the first of several eugenics-driven laws that allowed for the forced sterilization of inmates and mental hospital patients considered "unfit" for society. Stanley once said he believed at least 20% of inmates were "feeble minded" and lamented he could not sterilize more inmates than he was legally allowed. Those he could not forcibly sterilize, he attempted to talk into the procedure. In 1935, he put up a poster in the prison yard extolling the virtues of the surgery: "This simple operation prevents the man from producing children, but it does not interfere with his normal pleasures. In fact, it is claimed that sexual vigor is increased." In two decades, Stanley sterilized 600 prisoners, far more [than] other California prisons.