552 APPENDIX 



of the bottles so that cases can be stacked even though stoppers and delivery tubes are 

 still in place. The case should have stacking loops at the corners and should be of light, 

 but sturdy, construction. Stainless steel wire cases are perhaps the best, but other 

 materials, such as plated, tinned, or galvanized wire, may be suitable. 



Our design of bottle cases was adapted from milk bottle carriers except for the 

 extension of the bottom. Each case holds 25 pint bottles. The case is constructed 

 of stainless steel wire and has stacking loops at the four corners. 



Racks. — Racks for supporting mouse cages must be designed to fit the type of 

 cage that is to be used. Spacing between cages should be large enough to permit 

 easy removal of a single cage. Space between shelves should be at least one inch 

 greater than the over-all height of the cage unit (with cover and water bottle attached). 

 The top shelf of a rack should be low enough so that cages can be removed from it 

 by a caretaker of average height. If upper shelves are high, a stepladder or similar 

 device will be necessary. 



Rack shelves may be solid or they may be made of bars (pipe) . Solid shelves 

 should be removable for cleaning. Bar shelves should be permanently fixed, 

 with the bars close enough to support the cages firmly, but far enough apart to allow- 

 easy cleaning. Shelves of either type must be strong enough to support the load 

 without undue bending. 



Racks may be provided with casters, they may be suspended from wall or ceiling, 

 or they may stand on the floor. Suspended racks leave the floor free of obstructions, 

 but they also limit the flexibility of space in any room. Racks on casters must be re- 

 stricted in size to permit mobility. Caution must be used in their handling since they 

 can be easily upset if the floor is not level or they are pushed laterally instead of longi- 

 tudinally. Fixation of two racks side by side by screws or clamps promotes stability 

 and yet allows access from adjacent aisles. 



Solid shelves help to prevent dust, nesting material, or feces from falling from upper 

 cages to those below, but they also reduce the circulation of air around the cages. 

 Bar-type shelves allow maximum circulation of air, but they do not prevent material 

 from falling from upper cages to the cages below. If cages are constructed so that 

 material cannot be pushed out by the mice, bar-type shelves may be adequate. 



The racks used in our mouse rooms are built in sections with 7 shelves per section 

 and room for 6 double or 12 single cages on each shelf. Thus 84 cages or 42 boxes 

 (2 compartments per box) are in each section. 



Food dispenser. — Food should be given a minimum of handling between the bag 

 and the food hopper. Food in open boxes on top of a dispensing table or containers 

 below the top can be easily contaminated. For this and other reasons it is best to use 

 a container suspended above the table. The dispenser for food in our mouse room is 

 designed to hold 50 pounds of pellets (figure 87). The container is covered by a 

 hinged lid, and food is poured directly from the shipping bag into the dispenser. The 

 lower part of the dispenser is tapered on all four sides to about 3 by 4 inches, and an 

 adjustable gate attached to the body of the dispenser can be used to control the flow of 



