Modern ways of feeding laboratory animals.

There is a trend in the feeding habits of biologists-that is, in the way they feed their animals, not themselves-going back some 20 or 30 years. It starts with the homely methods of pet-keeping: for mice, bread soaked in milk with a handful of oats and an occasional lettuce or dandelion leaf; through the preparation of sticky mashes of various kinds, with or without supplements; the offering of dry powdered mixtures in little dishes or ingenious non-spill feeders; to the ideal of a compound cubed or pelleted diet, fed if possible without supplements from a hygienic wire basket, together with water from a bottle. The sticky mashes have been beloved especially of commercial breeders. They are less laborious than a varied diet and demand no special food utensils in the cage, but they are wasteful and unhygienic. Powders have to be mixed on the spot at frequent intervals and are easily fouled in the cage, more easily scattered and wasted. They are also open to the objection that the animal can pick out what it likes and leave the rest; a drawback that is easy to exaggerate.