Using a microcomputer and video camera to simultaneously track 25 animals.

A system that can simultaneously track about 25 animals with the position of each determined once a second is described. The system includes a 6809 microprocessor, OS-9 operating system and application programs written in assembly and BASICO9. The movements and changes in direction of the subjects can be determined and displayed in real time. The system has proven to be valuable in studying the chemotaxis of nematodes and should be applicable to the study of other animals that can be viewed with high contrast.