128 ORGANIC EVOLUTION — THE FACTORS 



hypothesis. They show that there is none of the 

 alleged independence of the reproductive cells, but that 

 the two sets of cells are in close communion. They 

 prove that while the reproductive cells multiply and 

 arrange themselves during the evolution of the embryo, 

 some of their germ-plasm passes into the mass of 

 somatic cells constituting the parental body, and becomes 

 a permanent component of it. Further, they necessitate 

 the inference that this introduced germ-plasm, every- 

 where diffused, is some of it included in the repro- 

 ductive cells subsequently formed. And if we thus 

 get a demonstration that the somewhat different units 

 of a foreign germ-plasm permeating the organism, 

 permeate also the subsequently formed reproductive 

 cells, and affect the structures of the individuals arising 

 from them, the implication is that the like happens 

 with those native units which have been made some- 

 what different by modified functions : there must be a 

 tendency to inheritance 'of acquired characters" (pp. 

 38-9). 



The above passage is somewhat obscure. Its meaning, 

 however, seems to be as follows : — Some of the germ- 

 plasm of the first-formed reproductive cells passes into 

 the somatic cells to the farthest limits of the organism. 

 If then, any part of the organism acquires characters 

 these are, by part of the germ-plasm there abiding, 

 conveyed back to the germ cells subsequently formed, 

 and thus acquired characters are transmitted. This 

 Mr. Spencer thinks is proved by what he imagines is 

 a fact, viz. that foreign germ-plasm is incorporated with 

 the somatic cells, whence it enters reproductive cells 

 subsequently formed, whereby the progeny of subsequent 

 sires are infected with the characters of the first sire. 

 If my interpretation is correct, it must be admitted that 

 Mr. Spencer has here built a very pretty superstructure 

 on remarkably slight foundations. 



Professor Romanes {Contemporary Beview, April 1894) 



