The origin of this strain is KR1082 via CB51. KR1082 was maintained on plates for a period of approximately two years. After this time, DNA was made and the Tc1 pattern examined. The number of Tc1s found in KR1787 was greater than that found in KR1082. Perhaps as many as 30 additional Tc1s were visible in excess of those normally seen in N2 strains.