CARE AND RECORDING 479 



on which may be Hsted the data regarding the male and the numbers of the 

 females to which it has been mated. 



In addition to the individual cards a serial ledger should be maintained 

 in which all the litters are entered. A separate ledger may serve for each 

 stock or a continuous one for all stocks. 



Pregnant females should be given an individual pen in which to have and 

 rear their young. Experience will show that more and better young will be 

 raised to weaning age if this system is followed. The female's individual 

 card should be changed from the breeding pen file to that corresponding to 

 the new box when she is separated from the male. The new box number 

 may be noted on the male card to assist in locating the female at any time 

 before she is returned to the home pen. 



On the date of birth of a litter all the desired data should be recorded on 

 the individual card. The recording in the ledger may, if desired, be delayed 

 until the young are weaned. 



Consideration should be given to the following details for the satisfactory 

 care of mice. 



A well heated and ventilated room should be available. The temperature 

 should be approximately 72° at all times. If an automatic ventilating sys- 

 tem is not used, care should be used in ventilating the animal room by means 

 of windows. Avoid sudden changes in temperature and direct drafts on the 

 mice as they easily contract pneumonia. 



Take rigid sanitary precautions in the care of the boxes, bottles, goose- 

 necks and racks. If the water bottles are all filled at one time the sterilizing 

 of the goosenecks is advisable to prevent the spread of disease from one box 

 to another. Covers and hoppers should be cleaned at regular intervals. 



Food and water should be before the mice at all times. The selection of 

 the food may only be determined by experience as some strains will do better 

 on one diet than another. Soiled food remaining in the hoppers when the 

 boxes are changed should be discarded. 



Do not place too many mice in a single pen. Overcrowded mice often 

 become infested with mites or lice. These may be controlled by periodic 

 dusting with powdered tobacco or a mixture of i part of derris root powder 

 and 3 parts of talcum powder (it may be necessary to sterilize the ingredients 

 before they are used).' 



To obtain and maintain inbred strains, mate only brothers and sisters. 

 Mark all animals used for experimental or breeding purposes and make use of 

 individual cards and a ledger for complete records. 



