Experiments on the physiology and genetics of the smut fungi. Cultural characters. Part I.—Their permanence and segregation

Abstract

For some time the permanence of the characters of fungi when grown on artificial media has been the subject of research, and considerable discussion has taken place on the origin of new forms (saltation). Many types have been studied but there has been no case as yet in which the characters of the parent organisms or of the saltants have been shown to be inherited in a fashion similar to those of the higher plants and animals. The investigation, the results of which are being published under the above general heading, was begun in 1925, and had as its objects ( a ) the solution of the question whether any cultural characters found were inherited along mendelian lines, and ( b ) the breeding of certain strains for use in physiological experiments. The organisms used were the Covered Smut of Oats ( Ustilago levis , Kell. et Sw.) and the Covered Smut of Barley ( Ustilago hordei , Pers.). Certain cultural characters have been determined and experiments have been made which suggest that such characters are inherited in a Mendelian fashion. The first part of this evidence will be given here, namely evidence which suggests that the cytoplasm has no determining influence on these characters, evidence which shows that the characters of the strains have remained constant during the progress of the investigation, and, lastly, evidence from which it may be deduced that the segregation of these characters may occur in either of the "reduction divisions."