June 19, 1916 Correlated Characters in Maize Breeding 439 



hereditary tendencies with respect to the characters studied. The- 

 oretically this is only possible in asexually propagated groups. Ap- 

 proximately pure lines may be obtained where self-pollination is possible, 

 so that if correlations are found they may with assurance be considered 

 physiological. In maize, however, even to approximate pure lines 

 produces such abnormal conditions that some other method of study 

 must be sought. 



Even in maize it would seem that the question might be approached 

 by comparing the degree of correlation in types or varieties having a 

 relatively restricted ancestry with that observed in the perjugate genera- 

 tions of hybrids between two contrasting forms. 



An equally satisfactory method is to compare the degree of correla- 

 tion in the first or conjugate generation of a hybrid with that of the per- 

 jugate generations. Where the conjugate generation is all descended 

 from a single cross, the gametic differences should be no greater than self- 

 pollinated progenies of the parents. 



Unfortunately in our experiment the number of first-generation indi- 

 viduals w'as too limited to detect any but relatively large correlations. 

 Wherever data were available, additional evidence has been presented 

 from the behavior of the original varieties. Although a large number 

 of plants of both parent varieties have been grown and measured, the 

 data have been secured in different localities and in different years, a 

 fact that renders many of the measurements unavailable for these studies. 



DESCRIPTION OF MATERIAL 



The hybrid that afforded the data for the present paper was a cross 

 between Waxy Chinese and Esperanza, two varieties of maize separated 

 by a number of definitely contrasted characters. The hybrid was made 

 at Lanham, Md., in 1908. 



The peculiarities of the Waxy Chinese variety (PI. LV-LVI) have 

 been described elsewhere (Collins, 1909). 



The particular plant used as female parent of the hybrid was grown 

 from the original seed imported from China. The individual notes taken 

 in 1 908 give the following details : 



Height, 167 cm. Length of fifth leaf from the top, S>7, cm. Width oF fifth leaf, 9 cm. 

 Leaf sheath smooth. Nodes above the ear, 4. Suckers, o. Plant rather open, but 

 distinctly one-sided. 



The Esperanza variety belongs to a peculiar type of maize that appears 

 to be confined to the table-lands of Mexico, the Zea hiria of Bonafous 

 (1829). This variety was obtained in 1906 from Esperanza, Pueblo, 

 Mexico, by Mr. H. Pittier, of the Bureau of Plant Industry (PI. LVIII 

 and LIX). 



The plant that was the male parent of the hybrid was raised from seed 

 grown at Lanham, Md., in 1907. Regarding the 1907 plants, the notes 



