CHROMOSOME NUMBERS IN THE ANNONACEAE

Abstract

which had induced them. When isolated from the normal stem tissue and grown in vitro, the induced tumors lost their characteristic structure and reverted to the structureless condition of the original tumor tissue. The theory is put forward that induced tumors may be composite structures into the make-up of which both normal and tumor tissue enter, the xylem and chlorophyll-bearing layer arising from normal stock, the cortex from the tumor scion. The normal tissue in these tumors would thus be analogous to the stroma in malignant tumors of animals.