"Section 1. Physicians appointed for hospital residency other than senior residency in any training hospital under the Department of Health and Department of National Defense must be duly licensed physicians who have graduated from recognized medical schools. They shall be appointed for a period of one year, renewable every year, in the discretion of the Secretary of Health or Secretary of National Defense as the case may be: Provided, however, That the total duration of their appointments shall not exceed a period of three years: Provided, further, That in the computation of the three-year period, the period of time during which the appointee may have served as resident in any clinical department or section of any government training hospital be included. Provided, lastly, That this three-year limitation shall apply only to all appointment for residency hereinafter made.

"Sec. 4. The Secretary of Health and the Secretary of National Defense are authorized under this Act to designate the medical training hospitals under their respective departments."