11 



at the Now York ExporinuMit Station in ISSH, and Burrill reported 

 instances of this intliience in 18S7; Tracv in 1887; Kellerinan and 

 Swino-l(> in 1888; and Hays in 1889. In i^\)'2 MoCluer published tiie 

 results of experiments conducted at the Illinois Experiment Station, 

 witli photojiiaphic ])lates showinjr the extraordinary effect which 

 Black Mexican sweet corn used as the pollen parent exerted on kernels 

 of a white dent race. 



\VhiU> many of the experiments are faulty on account of doul)t as 

 to the purity of the seed used, it will he seen from the above review 

 that in the experiments of Vilmorin, Kornicke, and possibly Hilde- 

 brandt, careful attentioii was oiven to such features, and the work of 

 these experimenters is thus not open to this ol)jection. While the 

 majority or all of the American experiments are open to this criticism, 

 3'et the fact that an innnediate influence does seem to occur has been 

 observed so often and so widelv in America that, even considmMngf the 

 possi])ility of error in some instances, it is nevertheless probal)le that 

 in many cases the efi'ect observed must have })een due to xenia. With 

 all this weight of evidence favorin^if the occurrence of xenia, it was, 

 nevertheless, doul)ted In' very many botanists because of its apparent 

 contradiction of well-established laws of reproduction and embryology 

 and ])ecause of the great possibility of error in experiments of this kind. 

 Under these conditions it was highly desiral)le that some interpreta- 

 tion of the phenomenon ])c ol)tained, and happih^ the discovery of 

 double fecundation seems to furnish a reasonable explanation of a 

 majority or possi})ly all of the cases in which xenia has been proved 

 to occur. 



In the preliminar}' note by Prof. De Vries, above referred to, he 

 describes an experiment conducted in the summers of 1898 and 1899 in 

 crossing a pure race of sugar corn known as " Blanche" with an ordinary 

 starch corn. The tassels of the majority of the plants of the sweet 

 corn were removed, and the ears were then dusted from time to time 

 with pollen from a variety of starch corn. In this way De Vries 

 obtained ten mixed ears bearing grains ridged and furrowed, resem- 

 bling pure sweet corn, together with others which were smooth and 

 filled with starch, like the kernels of the male parent. These kernels 

 resemljliug the male parent were cultivated in the summer of 1899 and 

 found to be true hybrids. The sweet corn which was used in this exper- 

 iment as the mother parent was found to remain pure and true to 

 seed in the summers of both 1898 and 1899. In such cases where the 

 direct influence of the pollen occurs, De Vries concludes that the 

 change is simply a case of the development of a hybrid endosperm, 

 and that we have here an experimental proof in favor of the occur- 

 rence of double fecundation, as described by Nawaschin and Guignard 

 in Lilium and Fritillaria. 



Shortly after the appearance of De Vries's paper, Correns's artiole 



