THE LAWS OF HEREDITY 



ultimately develop to produce the entire organism 

 with its varied members and bodily organs; but 

 the remaining and essential portion of the germ- 

 plasm maintains its integrity as germ-plasm, di- 

 viding to produce cells of its own kind, even as a 

 bacterium or an ameba divides, and constituting 

 an unbroken series of germ-cells linking the 

 earliest ancestor of any line with the remotest 

 descendant. 



Parent and child are thus sprung from the 

 same germinal stream, and in the broadest view 

 they are not to be regarded as mother and daugh- 

 ter, but rather as sisters of the same fraternity. 



The child has the qualities and characteristics 

 of its parent not through any occult law of trans- 

 mission, but because they both draw their qualities 

 from the same germinal stream the perennial 

 stream of the ancestral germ-plasm. 



It is important to get this idea of the continuity 

 of the germ-plasm clearly in mind, for it furnishes 

 the clew to a clearer understanding of the mys- 

 teries of heredity than would otherwise be pos- 

 sible. 



MODIFICATION OF THE GEEM-PLASM 



It must at the same time be clearly borne in 

 mind, however, that the stream of ancestral germ- 

 plasm, which thus serves as the carrier of heredi- 

 tary capacities from generation to generation, is 

 not entirely beyond the reach of external influ- 

 ence, and does not remain absolutely unmodified 

 throughout indefinite periods of time. 



[265] 



