Abstract
The resistance of vegetative cells and of microcysts of Myxococcus xanthus to several destructive agents was compared. Fruiting-body microcysts were 300 times more resistant to 60 C, 5.4 times more resistant to ultraviolet light, and 19.3 times more resistant to sonic vibration than were vegetative cells. Whereas resistance to sonic vibration developed during the conversion of rods to refractile spheres, resistance to heat did not appear until after the conversion was complete. Both vegetative cells and microcysts of the yellow variant of this strain were more resistant to ultraviolet irradiation than was the tan variant.