INHERITANCE IN ABNORMALITIES 447 



of organic matter or the constitution of organisms. It is per- 

 fectly possible for organisms to exist in which hereditary varia- 

 tions occur during non-sexual reproduction, and in which these 

 variations can be accumulated through selection; for in the 

 characters here studied this does occur. No one therefore can 

 say a priori what characters must descend in this manner, what 

 in some other manner. 



It is then an open question whether a sunilar scheme of descent 

 may not be followed by other characters, either in this same 

 organism, or in other organisms. Jollos ('14) has raised the 

 question whether all the hereditary variations shown by Jennings 

 to follow upon conjugation may not be of the nature of abnor- 

 mahties. It is entirely possible that all show the same scheme 

 of descent as the 'abnormalities' considered in this paper; but if 

 so then the 'abnormal' cannot be characterized as the unusual. 

 In the same way it is possible that the hereditary differences 

 among the progeny of single exconjugants observed by Calkins 

 and Gregory ('13) may be of the same nature as these abnor- 

 malities. It is quite possible that lines might be 'abnormal' in 

 ways evident only through studj^ of the fission rate, or the like. 

 But with such a state of the case the distinction between abnor- 

 mal and iiomial becomes evanescent. 



The facts are, that in Paramecium as a result of conjugation, 

 there appear lines or races that are hereditarily diverse; and that 

 within some of these lines hereditary diversities likewise appear 

 even during asexual multiplication. Whether we can maintain 

 some special category such as 'abnormality' for all these cases, 

 can be discussed; but this does not do away with the facts as 

 to their existence and the scheme of their descent from genera- 

 tion to generation. 



It is of interest to compare the genetics of these abnormalities 

 in Paramecium with abnormalities in other organisms. Ahuost 

 all the characters studied by Morgan and his associates in Dro- 

 sophila, on which have been reached results of such immense 

 importance for the entire theory of genetics, may be charac- 

 terized as abnormalities. A large porportion of them show, as 

 is well known, typical Mendelian inheritance. Others show a 



