Tissue Cultures of Spermatophytes

.-The literature concerning the growth of tissues of the higher plants has been reviewed by White2 so recently that it seems unnecessary to repeat it here. Suffice it to say that after a long series of unsuccessful attempts White3 developed a technique by which he was able to secure continuous growth of tomato roots in nutrient solutions. However, in one sense White's results were incomplete for they did not produce buds and so never grew into complete plants. This point should not be labored, for true "tissue" cultures would be grown from tissues and not from organs, and it might be thought that White's cultures in which one organ continued to develop indefinitely were nearer true tissue cultures than if they had grown into complete plants. Admitting this possibility, it still has seemed desirable to be able to grow small bits of seed plants and to secure from them development into complete plants. The present investigation was made with that end in view. Methods.-Culture media. The solution developed by White3 was used in these trials. The following salts were used as indicated: