HANDLING OF KADlUlSOTOrKS WITH AMAIALS AND PLANTS 



131 



surfaces that have contact with urine may be coated with siHcone to 

 increase water repellency and expedite the flow of urine droplets; also the 

 hairs and skin platelets will stick to the coating and not be washed into the 

 urine (19). 



After the administration of some radioisotopes to animals, particularly 

 carbon 14, tritium, or radium, there may be radioactivity in the expired 

 air. Even where the levels are so low that no health hazard exists, there 

 may still be the possibility of cross-contamination of animals housed 



Fig. 4-9. Glass metabolism cage for the collection of feces, urine, and expired CO2 

 from small animals. {Courtesy of Atomic Energy Commission.) 



close together; this could interfere with the interpretation of experimental 

 observations. Where it is necessary only to dispose of expired gases, 

 ordinary cages may be employed utilizing hoods or other means of effec- 

 tive ventilation. If the animals are to be maintained for only 1 to 3 days, 

 an ordinary vacuum desiccator can be used wdth a pump for supplying air 

 and a collection device for trapping the expired gas for subsequent meas- 

 urement. For longer-term studies where excreta collections are also 

 recjuired, more elaborate cages are necessary, such as that illustrated in 

 Fig. 4-9. 



A useful cage has been described by Bollman (20) for restraining a rat 

 over several days while an indwelling tube is in place. It has proved 



