agreed with Weatherwax, with reservations; he still re- 
gards the direct descent of corn from teosinte as a dis- 
tinct possibility. 
The theory of common ancestry maintains that corn 
originated from a perennial, wild, corn-like ancestor, now 
extinct, and that this extinct ancestor, sometimes called 
pre-maize, in turn had an ancestor, likewise extinct, in 
common with teosinte and Tripsacum; also that the na- 
tive range of all of these species was Central America and 
Mexico. Actually the theory represents the application 
to the American Maydeae of the broad views of Darwin 
and earlier students of evolution. 
The factual evidence claimed by the proponents of this 
theory falls into two categories. (A) The three groups— 
corn, teosinte and Tripsacum—are very similar, except 
that each has modifications of its own which have led 
to the differences now found among them. For example, 
teosinte and Tripsacum have lost one member of each 
original pair of pistillate spikelets, but corn has not; most 
varieties of corn and teosinte have lost the terminal stam- 
inate portion of the lateral inflorescence (ear), but Trip- 
sacum has not. Weatherwax (41, 42) pointed out by way 
of explanation that, if we could restore to each of the 
three groups the primitive organs which have been mod- 
ified in evolution, they would converge in a common 
type, giving us an idea of the common ancestor. But 
more revealing, in our opinion, is the result that would 
be obtained by restoring the primitive organs of only 
corn and Tripsacum, omitting teosinte. ‘The common 
type towards which they would converge is the same as 
when teosinte is included. This fact is best explained by 
the hypothesis of the hybrid origin of teosinte, because 
this hypothesis holds that the characters of teosinte are 
merely a combination of those of corn and ‘Tripsacum. 
(B) It is stated that corn, teosinte and 'Tripsacum are 
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