182 On the Genetics of the Ciliafe Protozoa 



teleological interpretations of conjugation and other phenomena. 

 Whether conjugation is for the purpose of originating variations, or 

 for any other purpose, is to my mind an idle discussion : and I have little 

 liking for the "explanations" which have been given of the phenomenon 

 — explanations which seem to me to explain nothing and lead nowhere'. 

 So many real problems which may be attacked by means of experiment 

 are still unsolved, that I think the discussion of more remote problems 

 may be profitably postponed. 



131. No new light has been thrown upon the great problems of 

 organic evolution by a study of the ciliates. They have revealed no 

 real indication of the manner in which evolution has proceeded, or is 

 proceeding, within the group": a fortiori, they tell us nothing of the 

 process of evolution in general. The facts so far determined could, 

 indeed, be used with far greater force to support the doctrine of the 

 fixity of species. Moreover, even if it were possible to draw any 

 general conclusions from the ciliates themselves, it would not be 

 justifiable as yet to extend them even to the other groups of Protozoal 

 The ciliates are so curiously organized that in many ways they stand 

 alone among animals. What is true of ciliates is not necessarily — or 

 even probably — true of most other organisms. These will be unwelcome 

 sayings to many, but I believe they are true. And all will admit that 

 it is better to face the facts, however distasteful and uncontbrmable to 

 theory they may be, than to veil them with that former assurance con- 

 cerning organic evolution which, as is fast becoming evident, was chiefly 

 begotten of ignorance. 



' Compare for example ihe following: "Conjugation should be regarded as a set of 

 phjsico-chemical phenomena resulting in a sort of cellular purification" (Loisel, 1903). 

 "Conjugation appears to us as above all a set of chemical phenomena which counteracts 

 another set of chemical phenomena — .senescence" (Loiael, 1903 b), etc. 



^ I leave out of account the numerous fanciful speculations concerning the phylogeny 

 of the ciliates which, I know, afford satisfaction to many. I am here considering the facts 

 relating to the ciliates on their merits — apart from any preconceived interpretations. 



^ I believe there are few prutozoologists who would eudorse the opinion of Calkins 

 (1909) that Paramecium is "a typical protozoou." 



Imperial College of Science, London. 

 March, 1914. 



