tainly there is nothing in the evidence which is in conflict 
with the long-established and well-supported opinion 
that maize is an American plant—one which has perhaps 
been introduced into Asia twice: once in early post- 
Columbian times from the west by a land route, and a 
second time, perhaps somewhat later, when tobacco and 
the potato were also introduced from the east by sea- 
faring people. There is no factual evidence in conflict 
with this simple and rational explanation; but there is 
abundant evidence to support it. 
The door is still wide open for hypotheses about pre- 
Columbian culture diffusion between the Old World and 
the New, and the problem is an extremely important one 
which merits the most careful and critical attention on 
the part of scholars in several fields. The problem is not 
likely to be solved, however, by putting forward sweep- 
ing and sensational conclusions which are based upon 
inadequate and fragmentary evidence, especially when 
these are all too likely to be seized upon by other imagi- 
native writers who treat them as ‘‘evidence’’ or, worse 
still, as ‘‘virtually unassailable proof’’ (Zelinsky, 1950). 
Perhaps there has, indeed, been a pre-Columbian, 
trans-Pacific diffusion of culture and perhaps maize has 
been involved in it. To speculate upon this possibility 
certainly can do no harm. But fancy ought not to be 
confused with fact. The fact is, that, at the present time, 
there is no tangible evidence of any kind — botanical, 
archaeological, ethnographic, linguistic, ideographic, 
pictorial or historical — of the existence of maize in any 
part of the Old World before 1492. Until such evidence 
is discovered, any case for pre-Columbian, trans- Pacific 
diffusion must rest on evidence other than maize. 
{ 289 ] 
