In a great majority of cases the approximate minimum diameter for cutting which would be fixed by it forester would be somewhere between 16 and 30 inches, but say it were 18 inches, for example, it would not arbitrarily apply throughout the stand. Most trees with yellow, smooth bark and small heavy-limbed tops, perhaps partially dead, are mature regardless of their size. If small, they have been crowded or stunted and may as well be cut. Trees with large, healthy crowns composed of many comparatively small branches, and with rough dark bark showing no flat scaling, are sure to be growing rapidly, even if quite large. They are also less desired by the lumberman, who often calls them black pine or black jack, so may often be spared, without much sacrifice, for seed trees or in order to continue their rapid wood production. The seed tree problem in such a pine forest and under such a system as has been described is comparatively simple, for there are likely to be enough young trees of fruiting age left to fill up the blanks between existing seedlings. The density of the latter determines to a large extent the number and location of seed trees necessary, but there should always be two to four to the acre, even if this requires leaving some that would otherwise be logged. Under this system recurring cuts may be made at periods of perhaps 30 or 40 years, taking out each time the trees which have passed the minimum diameter since the last previous cut. It is obvious, however, that if the process is to continue indefinitely, protection must be absolute. Destruction of young growth will stop the rotation at the time the surviving older material is harvested. At each cut the brush should be disposed of with this end in view. If the stand is very thin it may not add much to the danger of fire and, especially if reproduction is difficult and requires shelter, may best be left spread on the ground at some distance from remaining trees. Otherwise, and this is the rule, it should be piled and usually burned. In this process and in logging every effort should be made to protect existing young growth from injury. Ground fires should be prevented now and always hereafter.