29 We may now pass, Venerable Brothers and Beloved Sons, to the consideration of a matter which has to do with the better management of the missions. Although on this subject Our immediate Predecessor has already given his advice and instructions, We desire to repeat them here because We rightly think them to be of the utmost importance in the fruitful exercise of the apostolate. Because in great part the success of Catholic missions among the heathen depends upon you, We desire you to have a better organization of your mission work than formerly, an organization which may serve to make easier for you in the future the work of propagation of Christian beliefs and the increase of converts to the Faith. Therefore, you must see to it that the missionaries are so distributed about that no part of the territory assigned you shall be neglected and that no part shall be left to be evangelized at some future and remote date. To accomplish this purpose, found many new stations (allowing the missionary to live in some central place) in the vicinity of which you may establish smaller houses, which can be left in charge of at least a catechist, each of which should have a chapel so that the missionary may from time to time come on certain fixed days to visit the people and exercise his ministry.
Source: Rerum Ecclesiae (Vatican.va)