Induced and Spontaneous Abnormality in Ciliates

Abstract

MOTTRAM^1,2, by means of various physical agents and by means of certain cyclic hydrocarbons—all factors, except one of the latter group, said to be carcinogenic—disorganised a ciliate and found some persistence of abnormality in the offspring of the disorganised cells. At first he named the ciliate Paramecium aurelia¹ and later Paramecium and P. colpoda Ehr., but finally adjusted the identification to "an amicronucleate race of Colpidium"². It is important to realize that his ciliate, being without a micronucleus, was intrinsically abnormal. In the reaction he suggested an analogy to tumour formation and surmised that where such abnormals arise spontaneously in culture there has been unwittingly some exposure to a carcinogenic factor.