154 THE STORY OF THE LIVING MACHINE. 



that the adult will contain, along with its differ- 

 entiated material, a certain amount of the origi- 

 nal physical basis of heredity which still retains 

 its original powers. This undifferentiated chro- 

 matin material originally possessed powers of pro- 

 ducing a .new individual, and of course it still 

 possesses these powers, since it has remained dor- 

 mant without alteration. Further, it will follow 

 that if this dormant undifferentiated chromatin 

 should start into activity and produce a new in- 

 dividual, the new individual thus produced would 

 be identical in all characters with the one which 

 actually did develop from the egg, since both in- 

 dividuals would have come from a bit of the same 

 chromatin. The child would be like the parent. 

 This would be true no matter how much this un- 

 differentiated material should increase in amount 

 by assimilation, so long as it remained unaltered in 

 character, and it hence follows that every indi- 

 vidual carries around a certain amount of undif- 

 ferentiated chromatin material in all respects iden- 

 tical with that from which he developed. 



Now whether this undifferentiated germ plasm, 

 as we will now call it, is distributed all over the 

 body, or is collected at certain points, is imma- 

 terial to our purpose. It is certain that portions 

 of it find their way into the reproductive organs 

 of the animal or plant. Thus we see that part of 

 the chromatin material in the egg of the first gen- 

 eration develops into the second generation, while 

 another part of it remains dormant in that second 

 generation, eventually becoming the chromatin of 

 its eggs and spermatozoa. Thus each egg of the 

 second generation receives chromosomes which 

 have come directly from the first generation, and 

 thus it will follow that each of these eggs will 



