The responses of onion and lily mitosis to coumarin and parasorbic acid.

A substance which shows comparable ontogenetic effects throughout the plant and animal kingdoms is valuable in interpreting certain fundamental growth phenomena. Colchicine is such a compound. Parasorbic acid is another, and is of even greater interest since it exhibits a range of effects far wider than that of colchicine. Parasorbic acid inhibits the growth of Amphibia and mammals (Heaton, 1929), destroys the mesenchyme of planarians (Hauschka, Toennies & Swain, 1945), and in tissue cultures inhibits the mesenchyme of embryonic chick (Medawar, Robinson & Robinson, 1943; Kuhn et al. 1943) and of mammals (Drew, 1927). It also inhibits the fermentation of yeast, the germination of pollen, and the germination of seeds (Kuhn et al. 1943; Kockemann, 1936). Parasorbic acid fed to rats has been shown to inhibit the Jensen sarcoma (Heaton, 1929), but in vitro evidence as yet is inadequate to demonstrate whether it selectively inhibits malignant fibroblasts (Cornman, 1945). Kuhn and his co-workers have shown that it does not attack Erlich carcinoma in tissue culture. The action of lactones such as parasorbic acid, in common with that of some antibiotics, may possibly be explained by their ability to react with sulphydryl groups (Cavalito & Haskell, 1945). In the above experiments the parasorbic acid was obtained from yeast, fruits, and animal tissues. Growth inhibitors are often reported in the literature (Amer. J. Bot. 31; suppl.), which may also prove to be related to parasorbic acid, extending even further its natural range of occurrence. The related compound, coumarin (see diagram), occurs in a number of plants, including sweet clover. It also has growth and germination-inhibiting powers (Kuhn