A COMMENTARY ON THE GENETICS OF 

 THE CILIATE PROTOZOA. 



By CLIFFORD DOBELL. 



PREFACE. 



For many years the ciliate Protozoa have been favourite objects of 

 study, and consequently they have furnished niucli curious information 

 concerning many problems of genetics. This information is, however, 

 to a large extent still unincorporated into current biological conceptions. 

 It has therefore seemed to me that it would not be an altogether 

 thankless task to attempt to extract from the immense and often hardly 

 accessible literature dealing with this group of organisms, such facts as 

 are likely to interest workers in the field of genetics ; and to present 

 these facts in a summary fashion easily comprehensible to the reader 

 unversed in protozoology. This is my aim in the following pages. 



From its very nature, therefore, it will be apparent that I do not 

 aim at setting forth in this article anything more than a selected body 

 of facts extracted from the works cited in the appended bibliography — 

 a consideration which I would ask the writers of these works to bear in 

 mind, if they should find much that they have contributed to our know- 

 ledge passed over in silence, or treated in cavalier fashion. Without 

 rigid and critical selection it would have been impossible to compress 

 all the accumulated facts of many years into anything less than several 

 bulky volumes. 



In the presentation of the facts I have adopted the following plan. 

 I have begun with a very brief general account of the Ciliata — in order 

 to make clear some essential peculiarities of these organisms : I have 

 then given a short account of the classical researches of Maupas' — since 

 current conceptions concerning the Ciliata are largely based (explicitly 



' I may remind the reader that the work on the Ciliata before the time of Maupas has 

 bpen exhaustively dealt with by Biitschli (1887-89). 



