to produce a given offspring (Tripsacum), then we find 
that the other parent could only have been either wild 
maize or teosinte. Of the two, wild maize is more promis- 
ing than teosinte as the putative parent. 
The chief evidence that indicates wild maize rather 
than teosinte (Zea mexicana (Schrad.) Reeves and Man- 
gelsdorf) as the non-Manisuris parent of Tripsacum is 
the nature of the phenotypic effects described below of 
two genetic types of Tripsacum chromosomes which we 
have experimentally superimposed as ‘‘addition mono- 
somics’” upon maize. Also the cytogenetic and morpho- 
logical evidence presented by Mangelsdorf and Reeves 
(1939), Reeves and Mangelsdorf (1959), that teosinte is 
a derivative of maize-Tripsacum hybridization suggests 
that it is of more recent origin than Tripsacum, and, if 
so, could not be the parent of Tripsacum. 
Although a detailed study of their phenotypes is still 
in the early stage, the morphological effects which we 
have been able to observe so far support our hypothesis 
as to the parents of Tripsacum. That is, there is one type 
of 'Tripsacum chromosome which is both genetically 
similar to maize and has ‘‘maizoid’’ effects which tend 
in the direction of wild maize. The other type seems to 
be genetically foreign to maize and has ‘‘manisuroid’’ 
effects tending in the direction of both teosinte and 
Manisuris. 
The effects suggestive of the characteristics of wild 
maize of only two addition monosomics of the maizoid 
type can be included in this preliminary report. First, 
the Tripsacum chromosome which is known to bear at 
least one locus, gi (maize marker liguleless;), and prob- 
ably many more, including G/z (maize marker glossy 
seedlings) and W’s3 (maize marker white sheaths) as found 
by Maguire (1962) has effects on the ear which we con- 
sider tend toward wild maize. Although the reduction 
[ 299 | 
