Preprophase Inhibition of Mitosis in Root Meristems

Abstract

Since 1925 A. P. DusTIN showed that trypafl.avine is able to effect, in the germinative layers of the mouse, an extensive pycnotic destruction of nu-cl~i just before the onset of prophase.Later work (by DusTIN and collaborators as well as by many other investigators) on animal material has made evident that a great many chemicals can have a preprophase inhibitory effect on mitosis.Among them, very different compounds such as nitrogen-mustards, sodium cyanate, potassium thiocyanate, phenyl-urethane and others (cf.Du-STIN P. Jr. 1947 a, b, c), develop their elective action on the preprophase nuclei even at very small doses.A more or less pronounced pycnosis characterizing their action, all these substances are defined as caryoclasic n or radiomimetic>> (DusiiN A. P., DusTIN Jr.).In plant cytology, our knowledge on the preprophase inhibition of mitosis by chemical agents is, on the contrary, quite inadequate.Such a situation results from the fact that, after the discovery of the cytological effect of colchicine (DusTIN, HAVAS and LITS 1937), plant cytologists have almost exclu-