Statement of Weismanns System (1886). 21 



stripped of all remnants of so-called Lamarckian 

 principles, we have next to consider what the theory- 

 means in its relation to germ-plasm. For, as before 

 explained, congenital variations are supposed by 

 Weismann to be due to new combinations taking 

 place in the germ-plasm as a result of the union in 

 every act of fertilisation of two complex hereditary 

 histories. Well, if congenital variations are thus 

 nothing more than variations of germ-plasm "writ 

 large " in the organism which is developed out of the 

 plasm, it follows that natural selection is really 

 at work upon these variations of the plasm= For, 

 although it is proximately at work on the congenital 

 variations of organisms after birth, it is ultimately, 

 and through them, at work upon the variations of 

 germ-plasm out of which the organisms arise. In 

 other words, natural selection, in picking out of each 

 generation those individual organisms which are by 

 their congenital characters best suited to their sur- 

 rounding conditions of life, is thereby picking out 

 those peculiar combinations or variations of germ- 

 plasm, which, when expanded into a resulting organism, 

 give that organism the best chance in its struggle for 

 existence. And, inasmuch as a certain overplus of 

 this peculiar combination of germ-plasm is entrusted to 

 that organism for bequeathing to the next generation, 

 this to the next, and so on, it follows that natural 

 selection is all the while conserving that originally 

 peculiar combination of germ-plasm, until it happens 

 to meet with some other mass of germ-plasm by mixing 

 with which it may still further improve upon its original 

 peculiarity, when, other things equal, natural selection 

 will seize upon this improvement to perpetuate, 



