48 



Life and Death, Heredity and Evolution 



Or observe an infusorian in which a new structure a pro- 

 jection for example has been produced through some ac- 

 cident (Figure 16). Will this thing be inherited at repro- 

 duction? It will naturally be carried on mechanically by a 

 single one of the individuals at reproduction, but the rest 

 do not produce it. After a thousand new individuals have 

 been produced, one of them may still have the new structure, 

 but no more than one. As a matter of fact, such a new 

 structure is usually gotten rid of completely in the making 

 over that accompanies reproduction (Figure 17). I have 



Figure 18. Reproduction in a deformed individual of Paramecium. 

 After the second division all descendants are normally formed. After 

 Jennings, 1908. 



examined a large number of such cases in the infusorian 

 Paramecium; the acquired peculiarities are not inherited 

 (see Figures 15 to 18). 



So there is no simple direct inheritance of acquired char 

 acters in the Protozoa, any more than there is in the higher 

 organisms. The progeny have to produce the characters 

 that they get, just as the parents did, and they usually 

 produce what the parent produced when it developed, not 

 what the parent may accidentally happen to have when it 

 divides. The progeny start where the parent did, as a 

 rule. 



Of course if we could get the fundamental constitution of 



