CHAPTEE II 



On d priori grounds we must conclude therefore, that 

 acquired variations are not transmissible, but here again 

 I must guard myself against misconception. In the 

 last analysis all inborn variations must of course be 

 acquired variations. For, eliminating the effects of 

 conjugation, since the child varies somewhat from the 

 parent, the constitution of the germ cell, whence the 

 child was derived, must also have varied somewhat 

 from the constitution of the germ cell whence the parent 

 was derived, and this variation can only have arisen as 

 the effect of some external cause or causes. By inborn 

 variations are therefore meant such variations in the 

 organism as result from changes in the constitution of 

 the germ cell whence it is derived, which changes in 

 the constitution of the germ cell may, for instance, be 

 produced by such alterations in the nutritive fluids as 

 are caused by exercising the arm muscles. What is 

 denied is, that such changes in the nutritive fluids as 

 the above, usually produce changes of such a kind in 

 the constitution of the germ cell as result, after con- 

 jugation and proliferation, in variations in the new 

 organism similar to those variations in the parent organ- 

 ism, which resulted from that exercise which produced 

 the alteration in the nutritive fluids. In other words, 

 though acquired variations may so alter the nutrient 

 fluids as to cause a secondary alteration in the consti- 

 tution of the germ cell, which in turn may cause it to 



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