184 Forestry Quarterly 



In several of the western nurseries, various adaptations and 

 changes in the "Pettis" frame have been made in recent years to 

 meet the requirements of local conditions and secure greater 

 efficiency and economy in nursery practice. Principal among 

 these changes has been the introduction of a "take-down" con- 

 struction by the Wind River Nursery, in Washington, designed 

 by A. R. Wilcox in November, 1912. This "take-down" feature 

 allows of taking the frames apart and storing them in compact 

 form in sheds in the winter, thus reducing deterioration. It also 

 makes the frames less bulky and clumsy to move, and makes it 

 possible for one man to do all the work of setting up and taking 

 down alone, which means an economy of labor at small nurseries. 



It has also been found desirable at many places where mice are 

 difficult to control, and particularly at Forest Experiment Sta- 

 tions, where the rodent factor must be absolutely eliminated from 

 experimental beds, to use y^- or ^-inch mesh galvanized hard- 

 ware cloth in place of the ^-inch mesh poultry netting specified 

 by Pettis, since the latter will riot exclude mice but only protects 

 against birds and large rodents. 



An improved type of frame which includes some original fea- 

 tures and which has proved itself particularly well adapted for 

 use at Forest Experiment Stations has been developed at the 

 Priest River Experiment Station in northern Idaho. As shown in 

 the accompanying diagram (frontispiece), the outside length is 

 the standard 12 feet, for economy in the use of lumber, since a 16- 

 foot stick will just make one side and one end piece. The width, 

 however, is 4 feet, 2 inches on the outside, or exactly 4 feet inside. 

 The lumber permits this width and by its use it is possible to use 

 48 square feet as the practically correct growing space in the 

 bed, in calculating density and yield of seedlings. If the inside 

 width were reduced to 3 feet, 10 inches by making the outside 

 measurement an even 4 feet, there would be a net loss of 2 square 

 feet from the area of the bed and the common practice of figuring 

 the area of a 4 x 12 bed at 48 square feet would introduce a 4 

 per cent error. 



, The frame is made low, 5 inches being allowed between the 

 top and the bottom side pieces, as shown in the diagram, being sim- 

 ilar in this respect to the "Pettis" plan. This low side is particu- 

 larly desirable in experimental beds, since it permits of reaching 

 all parts of the bed easily and quickly in making germination and 



