Gibberellin: Effect on Diffusible Auxin in Fruit Development.

Diffusible auxin is not present in tomato flowers at anthesis, but significant amounts can be obtained after the plants are treated with gibberellin. The early growth of the ovary in plants treated with gibberellin corresponds closely with growth after pollination and fertilization; the amounts of diffusible auxin are not significantly different over a period of 22 days.

Increase in Diffusible Auxin after Treatment with Gibberellin.

When dwarf pea plants, normal pea plants, and sunflower plants were treated with gibberellin, they yielded 3, 2, and 10 times more auxin, respectively, than untreated plants.

A SUGGESTED STERILITY TEST FOR PENICILLIN.

The proposed sterility test for penicillin, which employs cysteine (in the form of its hydrochloride) rather than Clarase, has proven to be satisfactory in our laboratories. The use of cysteine is advantageous because it is a compound of known structure and is readily available at relatively small cost. Suitable samples of Clarase or bacterial penicillinases are not as reproducible and the latter require much time and effort in their preparation.