"Germ Plasm has, therefore, had unbroken continuity 

 from the beginning of Hfe, and owing to its impressionable 

 nature it has inherited an organization of great complexity." 

 "In development a part of the germ plasm {i.e., the 

 essential germinal material) contained in the parent egg 

 cell is not used up in the construction of the body of 

 the offspring but is reserved unchanged for the formation 

 of the germ-cells of the following generation" (Weismann). 



The relationship between germ 

 plasm and body — or soma-plasm is shown 

 in the following diagram: — 



G is the fertilized ovum which divides 

 into body cells Bj and the germ-cells 

 Gi. Go, G3, G4, G5, are the lineage or 

 chain of germ cells and B2. B3, B4, B5, are 

 the lineage of body-cells. 



In development a part of the germ 

 plasm contained in the parent egg-cell (G) 

 is not used up in the construction of the 

 body (Bi) of the offspring, but is reserved 

 unchanged for the formation of the germ- 

 cells of the following generation. 



The difference between the old con- 

 ception and Weismann 's conception of 

 the relation between successive genera- 

 tions is naively put by Samuel Butler: 

 "It is not to say that the hen produces 

 another hen through the medium of an 

 egg, but to say that a hen is merely an 

 egg's way of producing another egg." 



Variations, according to the Germ 

 Plasm theory, are the result of the union 

 of the male and female germinal elements. 



The mixture of these plasms [amphimixis) in fertilization 

 gives great possibilities of variations arising from the differ- 

 ent combinations and permutations of the vital units within 

 the germ plasm. In single-celled organisms Weismann 

 states that the environment produces variations directly. 



Weismann, moreover, denies that acquired characters 

 are transmitted from parent to offspring. His argument is 

 as follows: "Acquired characters affect the body cells, and 

 the latter are simply a vehicle for the germinal elements,^ 

 which are the only things concerned in the transmission of 

 hereditary qualities. Inheritance, therefore, must come 



Fig-. 8. 

 Diagram illustra- 

 ting idea of con- 

 tinuity of germ 

 plasm. (Aft e|r 



Wilson). 



54 



