THE LAWS OF HEREDITY 



there are particles of matter to represent each 

 tissue or organ of the future organism, and that 

 these are in some way so mutually disposed as to 

 predetermine the future relations of the organs 

 that will develop from them. 



The modern physicist makes accurate studies 

 of the sizes of molecules and atoms and of their 

 numbers in a particle of matter comparable to 

 the smallest germ-cell, that enables us to compre- 

 hend how very complex a structure this germ-cell 

 may really be. 



He tells us, for example, that there lies at the 

 heart of the germ-cell a nucleus of infinitesimal 

 size, yet his microscope reveals various physical 

 structures within the nucleus which he calls 

 "chromosones" because they are readily colored 

 by stains. He believes that these "chromosones" 

 have to do with the transmission of characters, 

 yet he knows that they themselves must be enor- 

 mously complex ; and he makes calculations which 

 show that these chromosones, infinitesimal though 

 they be, are made up of millions of atoms. The 

 very smallest particle of matter that the micro- 

 scope reveals is estimated to contain "many times 

 twenty billion atoms. " 



So the germ-cell may be in reality an enor- 

 mously complex organism, containing thousands 

 of particles, each one of which is made up of mil- 

 lions of atoms. 



Such a computation, while it to some extent 

 satisfies the mind as giving tangibility to the sub- 

 ject, does not in any proper sense fathom the 



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