Whenever first mortgages upon real estate are held by the Bank of North Dakota securing a total amount of unpaid mortgage loans in the sum of at least one hundred thousand dollars, the industrial commission may cause such mortgages, or such of them as it shall think proper, but not less than the total amount of one hundred thousand dollars, to be assigned, together with the obligations thereby secured, to the state treasurer. The assignment of each such mortgage and obligation must be executed by the president of the Bank of North Dakota and must recite that it is made to “The state treasurer of North Dakota, and successors in office in trust, as security for bonds to be issued under the designation of bonds of North Dakota, real estate series, as provided by law”. The assignment must be duly recorded by the president in each county in which the lands affected by the mortgage are situated. As soon as such assignments are recorded, they, with the instruments assigned, must be delivered to the state treasurer, and at the same time the president of the Bank shall deliver to the state treasurer a verified statement showing the principal amount remaining unpaid on each such obligation secured by the mortgages so delivered.