Qualitative microtest for atropine esterase.

Seventy-three rabbits, 97 rats, and 124 guinea pigs were tested for the presence of atropine esterase by a new microhematocrit tube test, and the results were identical to those obtained by the agar plate test. Atropine esterase was present in 24 rabbits but was absent in all rats and guinea pigs. The microhematocrit tube test was simpler, faster, and less expensive to perform and as accurate as the agar plate test.