HUSBANDRY, EQUIPMENT, AND PROCUREMENT OF MICE 549 



initial cost may be somewhat higher than for cages made of other materials the invest- 

 ment in terms of durability is very reasonable. 



In general, a convenient size is one with a floor space 5 to 6 inches wide and 1 1 to 

 12 inches long. The wall height is essentially governed by two factors: the vertical 

 space available and the ability of mice to jump out of an opened cage. A wall 5 to 6 

 inches in height is a workable compromise. 



The transparent plastic cage is molded with rounded corners and reinforcing struts 

 at points of stress. Such cages can withstand temperatures which adequately sanitize 

 the cage provided the heat is applied when the cage is wet. The cage can be broken 

 if it is dropped or struck against a hard surface. Care must be exercised in handling 

 in order to maintain transparency. 



Both the stainless steel and the plastic cage are manufactured in the two-compart- 

 ment form. The use of such cages increases the efficiency of handling since two 

 cages are taken to and from a shelf in a single motion. The users of two-compartment 

 cages rapidly adapt themselves to a system of cage designation which minimizes the 

 number of empty compartments in a given shelf space. 



Fig. 89. Cage covers with attached food hopper showing stacking arrangement for 



MACHINE WASHING. 



Covers. — The type of cover (figure 89) used on the cage is second in importance only 

 to the design of the cage itself. Many types are currently in use. Some covers are 

 attached by hinges, but in most instances they are separate. Covers fabricated of 

 some type of metal are used almost universally. Wire mesh, expanded metal, punched 

 sheet metal, and wire grid are perhaps the most popular. Where cages are suspended 



