That's a very interesting document. The resumption of silver dollar coinage after the Pittman Act silver ran out in 1928 was made possible by the Thomas Amendment to the Agricultural Adjustment Act. The AAA was one of FDR's host of "alphabet soup" roster of bills to revive the American economy and bring relief to the unemployed. Not all were successful, but the mere fact that someone was doing something was encouraging after his predecessor's reluctance to interfere with the natural order of things during a time of unprecedented crisis.
The Thomas Amendment was tacked on o the larger AAA legislation to provide for the purchase of silver above market value. FDR directed that the metal be coined into silver dollars, perhaps to make the effect of such purchases more visible, but the coining mandate was removed in 1935. Thereafter, silver bars stood in for dollar coins, and the text on the silver certificate notes was amended accordingly.