compacted and which is recognizable as an ear of maize. 
What conclusions can be drawn from this series of 
transition forms which occurs in maize-teosinte hybrids? 
Collins was cautious on this point, stating that these in- 
termediate forms are of value primarily in throwing light 
upon the morphology of the ear and explaining its evo- 
lution in a mechanical sense. Weatherwax (18) was even 
more circumspect in his statement on this subject, which 
follows: ‘‘Hybrids between maize and teosinté will al- 
ways exhibit suggestive series; but, until we are more 
sure of the homologies between these two genera, it is 
futile to expect much information from the hybrids, for 
they will be speaking in a language that we cannot un- 
derstand. ’’ 
Now, when the homologies of maize and teosinte are 
somewhat better understood than they were two decades 
and more ago, and when the role of genetic mechanisms 
in evolution has also become much clearer, speculation 
on the meaning of the hybrid forms may be permitted. 
If maize has originated from teosinte under domesti- 
cation, as some students of the problem have assumed, 
then hybrids of the two species are capable of revealing 
something about the nature and extent of the genetic 
changes which have occurred. If we accept this inter- 
pretation we need only to state here that the genetic 
changes involved have been numerous and far reaching 
in their effects, and that the period of domestication of 
maize has either been very long indeed or mutations must 
have occurred at an unprecedented rate, for maize differs 
from teosinte by numerous genes distributed among a 
number of different chromosomes. If on the other hand 
teosinte is the product of the hybridization of maize and 
Tripsacum, as postulated by Mangelsdorf and Reeves 
(18), then hybrids of maize and teosinte simply show the 
effects which are produced upon maize by various doses 
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