Serum of cattle mixed with a pilocarpine solution shows no more alkaloids present if tested directly with an alkaloidal reagent (potassium mercuric iodide) after about one hour.
Serum of rabbit which binds more pilocarpine can not be tested directly in the same way, as the reagent splits off the bound alkaloids. The binding is looser in this case than in the case of serum of cattle.
In both cases the alkaloid is, however, not decomposed but can be recovered by precipitating the serum. If the serum—alkaloid mixture stands for about a day or longer a partial decomposition takes place.