30 



xcnia plainly in producinir smooth kernels like the male parent, and 

 in being changed in color. 



DISCUSSION OF RESULTS. 



The experiments of the writer are in many cases open to the com- 

 mon criticism that the seed used Avas not known to l)e pure. In a 

 num))er of instances, howeyer, practically all of the possibilities of 

 error were eliminated. In experiment 10a, where marked xenia 

 occurred in the color of the aleurone layer, the seed from which the 

 mother plant grew was from an ear of a pure race artificially inbred 

 the previous year and thus known to be true to type. The year in 

 which the cross was made, furthermore, no variation from the t3'pe 

 was observed in inbred ears, but some kernels on ears open to cross- 

 fertilization with adjoining races showed xenia, as would be expected. 

 In the case of Hickory King 9 X Cuzco 759 $ (experiments la, lb, and 

 Ic), where xenia was shown in the color of the aleurone layer, the seed 

 used, while not previously cultivated by the Avriter, was produced b}- 

 a careful seedsman who is known generally to use considerable care 

 to grow pure seed. Inbred ears the same season showed no variation, 

 and all of the kernels which showed xenia were found to be true 

 hybrids, so that the possibility of error in this case is reduced to a 

 minimum. The production of kernels resembling svreet corn on ears 

 of Gilinan Flint, produced from seed which had been inbred the pre- 

 vious year and thus known to be pure, is also considered by the writer 

 to be an undoubted case of xenia. (See p. 291.) The same is true of 

 the crosses of sweet corn with dent corn occurring in a field of sweet 

 corn grown from seed of known purity by Mr. J. C. Bradt and 

 examined by the writer. (See p. 241.) The other cases in which xenia 

 has apparentl}^ occurred in the experiments of the writer, while open 

 to some doubt, are, it is thought, more reasonabl}^ to be explained as 

 caused by xenia than in any other way. The conclusion has, there- 

 fore, been reached by the writer that xenia does occur in maize, what- 

 ever its interpretation ma}^ be. 



In all of the cases observed b}' the writer no exception has been 

 found to the rule first asserted by Koruicke, that xenia is shown only 

 in the endosperm, the portions of the kernel outside of the endosperm 

 remaining unaffected. "Nach meinen Beobachtungen haltc ich es 

 aber gleichwohl fiir wahrscheinlich, dass der Mais, welcher einen 

 gefarbten Inhalt der Kleberzellen hat, sich theilweis direct vererbt, 

 aber auch nur dieser.''^ Color in the endosperm is frequently trans- 

 mitted as xenia, but color in the pericarp apparently can not be thus 



'Kornicke, 1. c, p. 70: "According "to my observations I consider it, however, to 

 be probable that only in that maize in which the contents of the cells of the aleurone 

 layer are colored is there an immediate effect of pollen." 



