THE BREEDING OF MICE IN LABORATORIES 53 



side in each pan. These pans with the contained cages are 

 kept upon racks of dimensions to accommodate them. 



The cage proper has a sloping front provided with a gal- 

 vanized-iron door which is held shut by gravity and the 

 weight of the water bottle. The iron door is convenient as a 

 memorandum space for numbers or notes not recorded in the 

 official register. 



A dog biscuit is wired to the rear wall. The cage is pro- 

 vided with a handful of shredded tissue paper for nest ma- 



Fig. 10. Wire mouse cage used at the Bussey Institution. 



terial and with a feed dish. A numbered metal tag for cage 

 identification is wired to the sloping front, or the number 

 may be painted on the iron door. 



Once a week the cages should be cleaned with a stiff brush, 

 provided with fresh nesting tissue, fresh sawdust, and clean 

 food dishes, and about once a month they should be washed. 



Sanitary Precautions. Because mice are subject to several 

 infectious diseases, cages should be of a material which may 

 be readily sterilized. If cages are made of metal they may 

 be sterilized by immersion in boiling soapy water, brushing, 

 and then dipping in a solution of "Kreso" or other disinfec- 

 tant. Cages should be disinfected at least once a month 

 in absence of disease and oftener if the colony is infected. 

 Cages in which diseased animals have lived should be dis- 

 infected immediately. 



Animals dying from no matter what cause should be 

 removed from cages at once, because the carcasses are often 

 partially eaten by other mice and disease may thus be spread. 



