METHOD OF OPERATION 127 



great number of generations in conditions other than those 

 that produced the modifications, JoUos holds that they must 

 have their seat in parts of the cell that are not permanent; 

 that is, in the cytoplasm or the macronucleus. The environ- 

 mental modifications he holds therefore to be essentially 

 transitory; he calls them therefore Dauermodifikationen^ 

 which may be translated "long-standing modifications." 

 These he holds "are only changes forced upon the organism 

 from the outside, which do not alter its potentialities, and 

 though they do for some time prevent these potentialities 

 from being realized, the latter finally overcome them."^ 



And since these modifications affect, as he believes, only 

 transitory parts of the organism, leaving the permanent genie 

 materials unchanged, he holds that they "are without signifi- 

 cance for the question of the heritable transformation of a 

 line of descent; for the question of the origin of species." 



This conclusion rests upon the assumption that the genie 

 materials of the micronucleus must retain permanently any 

 modifications that they undergo. This, however, is not a 

 demonstrated fact. It is certain from the fact of the inheri- 

 tance of environmental characters that genie materials some- 

 where in the organism are modified by the environmental 

 conditions. All genie materials come finally from the micro- 

 nucleus; if they are modifiable in one location they may be 

 modifiable in another. And if they can be modified in one 

 direction by certain conditions, they may well be modifiable 

 in a reverse direction by opposing conditions. The recent 

 discoveries as to inheritance in conjugation taken in connec- 

 tion with the facts as to modification by the environment, 

 certainly suggest an alternative theory to that of Jollos. They 

 suggest strongly that genie materials in the two nuclei may 

 become modified, as well as those elsewhere. 



