IN his recent communication1, Dr. Mather seems to have no argument against the applicability of ‘kinetochore’. He sponsors “centromere” largely because it is used by a number of investigators. But I, for one, am not convinced that it is the “best term in use to-day”. To Dr. Mather ‘centromere’ may imply a visible particle, but to many it will connote a part that is centrally placed in a topographical sense. No such meaning is of course intended. My advice concerning the confusion that may arise from the addition of still another to the series of words involving ‘centre’ rests on my experience as a teacher. Perhaps the validity of such advice will be more apparent if I point out that in 1936 Darlington2 himself used ‘centrosome’ when he evidently meant ‘centriole’. The argument that no such confusion has attended the use of a series of terms involving ‘chroma’ is not well chosen, for in one place in the same paper (p. 266) Darlington writes ‘chromosome’ when he means ‘chromomere’.