A function of the preprophase band of microtubules in Phleum pratense.

A study has been made of the microtubules of the preprophase band and the mitotic spindle in the meristematic cells of the root of Phleum pratense. The preprophase band in these cells is placed symmetrically round the nucleus although a great many of the cells divide asymmetrically. It is suggested that the function of the preprophase band is to orient the nucleus prior to mitosis. The function and formation of the tubules which are found in close association with profiles of smooth endoplasmic reticulum is discussed.