[President Heber J. Grant Diary]
After lunch we read the communication from President Rudger Clawson making a recommendation by the Twelve that Elders should be ordained Seventies before they go on missions. We approved of their recommendation. The letter was also signed by Elder J. Golden Kimball. The proposition is that the Elders shall be trained a full year or more before they are called on missions, and made Seventies before they go.
[Diary of Heber J. Grant, http://amzn.to/newmormonstudies]