Twenty years on--changes in laboratory animal science.

Changes in laboratory animal science in the 20 years since George Porter's death are reviewed, with particular emphasis on animal welfare. The need for a generally acceptable definition of animal welfare is emphasized and a new definition is propounded. The concept of stewardship as a basis for human-animal relationships is explored.

Transmission of B virus infection between monkeys especially in relation to breeding colonies.

Studies of B virus (Herpesvirus simiae) antibody in several species of macaque lead to the following generalizations. Newborn monkeys are not infected with B virus, even when born of seropositive mothers. Young monkeys remain uninfected until they become adults.

Use of portable filter units to control the animal house environment.

The application of portable recirculating filter units to the control of laboratory animal house environments was investigated. Under practical conditions such a unit effected reductions in the ammonia level and bacterial content of the atmosphere of a room housing rats.