Heredity in Protozoa 49 



the organism to change say the chemical nature of its 

 nucleus and cytoplasm we might expect it to develop in a 

 new way, and produce new structures ; and as this would be 

 repeated in later generations, we should have the new char- 

 acters inherited. But this is a deep and difficult matter; 

 we shall take it up later. What we wish to bring out now 

 is the fact that the mere existence of an acquired character 

 in the parent presents no reason for expecting the progeny 

 to produce that character anew, and that as a matter of 

 fact they do not ; such acquired characters are not inherited, 

 either in Protozoa or in more complex organisms. 



We have seen thus that the progeny do not receive their 

 organs ready made from the parent; that on the contrary 

 they start from just the same condition the parents did 

 an undifferentiated condition without organs, on the whole 

 and produce their characteristics anew. The ground for 

 their producing the same characteristics as the parents 

 lies precisely in this fact, that they start just as the parents 

 did. 



Having thus examined the groundwork for inheritance, we 

 wish to look at the matter more minutely. Is it true that 

 the offspring start just where the parents did, and that they 

 produce just what the parents did? Or is there a gradual 

 change as generations pass, so that evolution occurs? 



If the progeny begin just where the parents did and de- 

 velop in the same way, then if we begin with a single parent 

 and obtain from it great numbers of progeny in successive 

 generations, we shall find that they are the same at the 

 end as they were at the beginning; and that all are alike 

 (save in so far environmental differences have made diver- 

 sities). There will be no opportunity for some to be pre- 

 served because they are better fitted to live, while others 

 die because ill fitted. Is this the situation, or do inherited 

 variations come on as generations pass? 



