1. It has not been possible to demonstrate in rabbits affected with serum sickness any constant temporal relationship between precipitin and precipitinogen in the blood on one hand and of occurrence of serum sickness on the other hand.
2. It has not been possible to demonstrate any differences between the precipitin and precipitinogen curves in injected rabbits which develop serum sickness compared with injected rabbits which did not develop serum sickness.
3. There is therefore no evidence that we can directly associate the occurrence of serum sickness with the production or appearance of precipitins.