The maintenance of respiratory control at 25 degrees C by mitochondria from various animal and plant sources.

1. Mitochondria from four different animal and five different plant sources exhibit a wide variation in their capacity to maintain respiratory control at 25 degrees C. 2. Beef heart mitochondria, and pear and avocado fruit mitochondria exhibit the longest retention of respiratory control extending to periods of approximately 80 and 40 hr, respectively.