10 



such grains when the}' existed avus ven' inconstant, being liable to 

 vary from 1 to 60 per cent.-' The effect was limited to changes in 

 color of the kernels, in most cases the pollen used being from a black 

 corn in which this color existed in the substance of the kernel. No 

 conclusions were drawn except from experiments upon plats of maize 

 which when left exposed or fertilized with their own pollen repro- 

 duced the sort planted without change, thus showing the purity of the 

 races used. In 1867 Hildebrandt gave the results of an experiment 

 in crossing corn, using a 3'ellow race for the female and a dark brown 

 race as the male. In order to prove that the plants of the yellow 

 race, which he used as the female, had not been affected by previous 

 crossings, he pollinated some of the plants with their own pollen and 

 obtained ears on which all of the kernels were exactly like the mother 

 sort. Two ears which he obtained by fertilizing the yellow race with 

 pollen of the dark brown sort "had about half the kernels like those 

 of the mother sort or a little lighter, while the other half, scattered 

 about among them, were a dirty violet color. On these latter, there- 

 fore, the pollen of the brown-kerneled sort had exercised a direct 

 transforming inffuence." In 1872 Professor Kornicke,' in describing 

 his experiments, came to the conclusion that xenia is .shown in those 

 varieties of maize in which the color is in the aleurone layer of the 

 endosperm, and that the influence of xenia does not pass out of the 

 endosperm and show in any other part of the seed. 



In 1870 Kornicke grew a bed of Early Yellow Baden corn which 

 came entirely true to seed. In 1871 two beds of this seed were sown. 

 One bed was left open, to be pollinated by its own pollen, and all of 

 the ears of this came true to seed. In the second bed some of the 

 ears were pollinated with pollen of a reddish-black maize, the color of 

 which was in the pericarp and in the aleurone layer. The cross-polli- 

 nated ears developed yellowish-red and dark-red kernels, and also 

 kernels like those of the mother race. All of the ears of the red sort 

 from which the pollen was taken bore seed typical of the race, thus 

 demonstrating its purity. Kornicke criticised Hildebrandt's work, 

 above referred to, stating that the color in the variety which he used 

 was in the pericarp and thus could not be shown as xenia. He also 

 claimed that the seed used by Hildebrandt must have been impure, 

 and the results therefore faulty. 



Many American investigators have given some attention to the 

 immediate effect of pollen in corn; but few of the experiments are con- 

 clusive, as in most cases no attention was given to the purity of the 

 seed planted, so that the results may have been due to previous cross- 

 ings or to reversion. Sturtevant observed the occurrence of xenia 



1 Kornicke, Friedr. Vorliiufige Mittheilungen liber den Mais. Sitzungsberichte d. 

 niederrheinischeu Gessells. f. Nat. u. Heilkunde in Bonn, 1872, pp. 63-76. 



