100 



presented. Lack of space prevents a more critical and accurate 

 delineation of the entire matter. 



It is notable that a presentation of the importance of mutation 

 or " heterogenesis " as a means of origin of new species has also 

 been made recently by Korschinsky,* based upon historical evi- 

 dence in which he presents a number of well-authenticated in- 

 stances of mutations ; other aspects of the subject have been 

 brought out by Kolliker and Hartmann. 



It will be of interest in this connection to cite a recent sum- 

 mary by von Wettstein of present knowledge of the method of 

 origin of species as based upon information derived from the 

 study of plants. This writer lays emphasis upon the fact that 

 the significance of mutation must not be underestimated, and 

 calls attention to the well-recognized fact that alterations in. the 

 elementary qualities of species have been demonstrated to take 

 place only by hybridization and by heterogenesis (mutation). 

 Other methods may exist but they lack the absolute proof which 

 may be found in support of the two named. It is but fair to this 

 writer to say, however, that he does not ascribe the origin of all 

 species to any one cause, and that he lays great stress upon the 

 fixation of adaptive characters, as well as upon hybridization and 

 heterogenesis, as prominent among the factors to which new 

 species owe their origin among plants in a state of nature, f 



Since the above discussion was given to my colleagues before 

 the weekly Botanical Convention, Professor de Vries has kindly 

 sent me a supply of seeds of Onagra biennis {Oenothera L din- 

 ar ckiana), the parent type used in his experimental cultures and 

 also of five of the newly arisen species, viz: 0. brevistylis, 0. gigas, 

 O. lata, O. nanella and O. rubrinervis. These were sown in the 

 propagating houses of the New York Botanical Garden early in 

 May and a fine crop of the different forms is already to be seen. 

 These cultures will be most carefully observed, and the continued 

 behavior of the parent type and derived forms noted, with respect 



* Korschinsky, S. Heterogenesis und Evolution. Naturwiss. Wochenschrift, 14 : 

 273. 1899. Also Flora, 89 : 240-363. 1900. 



f Wettstein, R. von. Der gegenwartige Stand unserer Kenntnisse betreffend die 

 Neubildung von Formen im Pflanzenreiche. Ber. Deut. Bot. Ges. 18 : (184). 1900. 



