ACQUIRED CHARACTERS 73 



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 

 entire 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 

 delightfully simple explanation to rest upon. It is a 

 theory assuming that all parental somatic cells take 

 part in the formation of the new individual, hence it 

 was called "pangenesis," or origin from all. 



Nothing we have subsequently learned of minute 

 cell structure favors this hypothesis, while many facts 

 go quite against it. Moreover, it is directly opposed 

 to the theory of the continuity of germplasm so con- 

 vincingly set forth later on by Weismann. Darwin 

 indeed advanced it only in the most tentative way, 

 being entirely ready to see it abandoned at any time 

 for something better. It at least performed one valu- 

 able service to science, namely, that of demonstrating 

 how far investigators were from an adequate concep- 

 tion of any means by which somatic modifications might 

 become incorporated in the germ-cells. 



We must acknowledge, however, with Lloyd Morgan 

 that the fact that a mechanism for the transfer of 



