140 THE DIRECT INFLUENCE 



atypic forms were obtained by the treatment of 

 pollen; my own from ovarial injections which 

 might have acted upon the egg, or sperm, and 

 Tower's work was with both. 



The new forms of beetles and plants which 

 have thus been called into existence sustain the 

 following general relations to their environ- 

 ment and to the strains from which they were 

 derived : 



1. Some of the species dealt with were growing 

 in the open, and domesticated forms were not in- 

 cluded in the experiments. 



2. The newly arisen or modified characters 

 maintained their distinctive appearance when 

 crossed with the parental strains; in some no re- 

 versions have yet been shown. 



3. Discontinuous departures induced by ova- 

 rial treatments in plants were full and constant 

 within the hmits of fluctuability with the first 

 generation. Similar abruptness of divergence is 

 exhibited by beetles in some cases, while in others 

 more than one generation, after removal from 

 experimental conditions, was necessary to secure 

 full expression. 



4. Many aberrations induced by irradiation in 

 plants and by climatic effects in beetles were of 

 the nature of closely continuous variations, the 

 range of which was widened by the exciting 

 agent. Some of the derivatives of Penstemon 

 may prove to be of this character. The single 

 derivative of Oenothera biennis obtained by ova- 



