A continuous culture system has been developed and tested for its usefulness in studying the degradation of oil and hydrocarbons. Both octane and diesel oil have been degraded in this system at measurable rates. Changes in these substrates and in the bacteria attacking them could be readily monitored and characterized. Oil and hydrocarbons could be degraded without mechanical dispersion and continuous culture enrichments were readily obtained as part of the degradation process. Sequential continuous culture systems have also been developed and tested successfully. An artificial oil has been developed to aid in the study of the bacterial mechanisms for degrading oil. A successful fish embryo bioassay has been developed and it has been shown that water extracts of oil and toluene interfere with embryological development. Oil degradation products also interfere with development but in a different manner. (Author).