METHOD OF OPERATION 129 



generations, any individual contains less than one-thousandth 

 of the original body material ; all the rest is new. After fifteen 

 generations the amount of old material remaining in any 

 individual is less than one thirty-two-thousandth of the origi- 

 nal body. Yet at these times there is still a marked distinctive 

 effect of the original body material; the size is not yet that 

 which the nucleus tends to produce. Clearly, either this 

 original body material has a great effect even in enormously 

 high dilutions; or what seems rather the case, some part of it 

 has the power of reproducing itself true to type during divi- 

 sion, just as does the genie material of the nucleus, so that we 

 must call it also genie material. This genie material of the 

 body is either the cytoplasm itself, or some remnants of the 

 old macronucleus. But this original body material gradually 

 loses its distinctive effect, through coming under the influence 

 of the nucleus. After three or four weeks or twenty to thirty 

 generations, it is completely dominated by the new nucleus. 



With these facts in mind, return to our question: Are the 

 inherited environmental characters the result of modification 

 of the reserve genie materials of the micronucleus, of the 

 active genie materials of the macronucleus, or of the genie 

 products present in the cytoplasmic body ? 



If the environmental modifications are in the genie mate- 

 rials of the cytoplasm only, we should expect the acquired 

 characters to disappear in twenty to thirty days, since we 

 know from what happens at conjugation that by the end of 

 such a period the nucleus has taken full control. Again, if the 

 acquired characters are in the active macronucleus only, they 

 would disappear at once when the macronucleus disappears. 

 If they are due to modifications of the micronucleus, they 

 would disappear only when some new influence modifies this 

 micronucleus. 



