SOME years ago I published an analysis of structurally changed types of Pisum sativum based on cytological observations1. One of these, structural type four which had arisen in the variety Extra Rapid, was reported as having chromosomes 3 and 5 interchanged, according to my notation. Recently, Lamm2 and Nilsson3 have challenged this statement, and on the basis of their genetical evidence claim that the K line (chromosomes 1 and 2 interchanged) and the Extra Rapid translocation have the chromosome carrying the GP factor, chromosome 2 on my notation, in common, and predict that the cross Extra Rapid × K should have an association of six chromosomes.