Feeding, Breeding, and Development 19 



welfare of the mice than in cold weather. The animals 

 attend faithfully to their own toilets, and usually keep them- 

 selves scrupulously clean. 



For water and food dishes I have used heavy watch glasses 1 

 5 cm. in diameter and \ cm. deep. They are convenient 

 because they are durable, easily cleaned, and not large enough 

 for the young mice to drown in when they happen to spin into 

 one which contains water. It is said that mice do not need 

 water, but as the dancers seem very fond of a little, I have 

 made it a rule to wash the watch glasses thoroughly and 

 fill them with pure fresh water daily. The food, when 

 moist, may be placed in the cages in the same kind of watch 

 glass. 



There is no need of feeding the animals oftener than once 

 a day, and as they eat mostly in the evening and during the 

 night, it is desirable that the food should be placed in the 

 cage late in the afternoon. For almost a year I kept a pair 

 of dancers on "force" 2 and water. They seemed perfectly 

 healthy and were active during the whole time, but they pro- 

 duced no young. If the animals are kept as pets, and breed- 

 ing is not desired, a diet of " force," " egg-o-see," 2 and crackers, 

 with some bird-seed every few days, is likely to prove satis- 

 factory. As with other animals, a variety of food is beneficial, 

 but it appears to be quite unnecessary. Too much rich food 

 should not be given, and the mice should be permitted to 

 dictate their own diet by revealing their preferences. They 

 eat surprisingly little for the amount of their activity. I have 

 had excellent success in breeding the mice by feeding them 

 a mixture of dry bread-crumbs, "force," and sweet, clean oats 

 slightly moistened with milk. The food should never be 

 made soppy. A little milk added thus to the food every other 

 day greatly increases fertility. About once a week a small 



1 Minot watch glasses. 2 A cereal food. 



