INHERITANCE OF ACQUIRED CHARACTERS 85 



forms where the parts represent cell complexes too 

 hopelessly differentiated to begin anew the unfolding 

 sequences of their elaboration. This difficulty was 

 a very real one in the mind of that famous nocturnal 

 inquirer Nicodemus when he asked: "Ho wean a man 

 be born when he is old ? Can he enter a second time 

 into his mother's womb and be born ? " 



Not only the development of the race which we 

 call evolution, but also the determination of the 

 individual in heredity, is a chain of onward-moving 

 sequences like the succession of events in history. It 

 is hard to see how recent events can influence pre- 

 ceding events. It is hard to see how the water that 

 has gone over the dam can return and affect the flow 

 of the river upstream in any direct way. It is like- 

 wise hard to see how differentiated somatoplasm, which 

 represents the end stage of a successive series of 

 modifications, can make any definite impress upon 

 the original germplasmal sources from which it arose. 



Darwin felt this difficulty and presented with apolo- 

 gies his provisional hypothesis of pangenesis in which 

 he assumed that every bodily part sends contributions 

 to the germ-cells in the form of "gemmules." These 

 gemmules, or hypothetical somatic delegates, then 

 reconstruct in the germ-cells the characters of the en- 

 tire body, including acquired modifications as well as 

 all others, and thus there is no reason why acquired 

 characters cannot readily be transmitted. Unfortu- 

 nately there is no tangible basis in fact for this de- 

 lightfully simple explanation to rest upon. It is a 

 theory assuming that all parental somatic cells take 



