METHOD OF OPERATION 133 



All this shows that other genie materials besides those in 

 the macronucleus may become modified by environmental 

 conditions. We have already given reasons for holding that 

 the cytoplasmic genie substances cannot be the seat of the 

 environmental modifications; for if they were, the modifi- 

 cations would be expected to disappear inside of about four 

 or five weeks. There remains only the genie materials of the 

 micronucleus itself. These reserve genie materials would 

 doubtless be modified less readily than the active materials in 

 the macronucleus; but there is no reason to reject absolutely 

 the possibility of modification for them, for they are literally 

 genie materials of the same type as those in the macronucleus, 

 since the two are halves of the same original nucleus. 



Furthermore, in certain cases a second-degree modification 

 is induced, of such a character as to suggest strongly that its 

 seat is in the micronucleus. In Uroleptus and in Spathidium 

 it has been shown that when the depression induced by bad 

 conditions is moderate in degree, it is completely lost at 

 conjugation when the macronucleus is replaced. But if the 

 depression has become very severe, it does not fully disappear 

 at conjugation, even though the macronucleus is then re- 

 moved. The condition of the animals is improved, but a con- 

 siderable degree of depression remains and continues to be 

 inherited. This is what we should expect if the environmen- 

 tal conditions first modify the genie materials of the macro- 

 nucleus, then if severe and long continued, modify the 

 reserves in the micronucleus. 



The facts therefore appear to point to the following situa- 

 tion. Environmental conditions, so far as they induce inher- 

 ited modifications, first alter the active genie materials of the 

 cytoplasm; such modifications last but a short time. Later, 

 after acting longer, they alter the genie materials of the 

 macronucleus; such modifications disappear with the disap- 



