Kansas Dniversity Science BeiLETiN. 



Vol. IV, No. 1. MARCH, 1907. I ^';fL° xiv ^Na i! 



ON HEREDITY IN CERTAIN MICRO-ORGANISMS. 



BY MARSHALL A. BARBER, 



Professor of Bacteriology, University of Kansas. 

 With plates I to IV. 



^ I^HE aim of the work described in this paper has been to 

 -*- conduct with certain micro-organisms investigations on 

 heredity similar to those long practiced with higher plants 

 and animals. From the offspring of single varying cells new 

 races of yeast and bacteria have been obtained, which differ 

 morphologically and physiologically from the type, and this 

 paper is mainly given to a study of the origin and charac- 

 teristics of these new races. 



In order to accomplish this work, involving as it does the 

 selection and isolation of single varying cells lying among 

 thousands of normal ones, a new method of isolation had to 

 be devised, a method which is described in another part of 

 this paper. 



The investigations described below have had to do princi- 

 pally with the yeast Saccharomyces annmalus and the bacterium 

 Bacillus coli comjnunis ; though some work was also done with 

 B. tyj^hosus and a large, spore-forming bacillus, probably B. 

 megatherium. In every case the work was done with abso- 

 lutely pure cultures, known to be such because known to be 

 the descendants of single isolated normal cells. 



In reviewing the literature on this subject, I shall confine 

 myself largely to those relatively few papers which deal with 

 the heredity of new races which have apparently arisen spon- 

 taneously from cells varying independently of the environ- 

 ments, and I shall omit the large number of publications 



(3) 



