merated and discussed, with special attention given to 
the botanical literature and the question of geographic 
origins. The high development of agriculture and the 
great diversity of habitat in Mexico are favorable for the 
development of a great variety of cultivated plants. Over 
eighty species are listed, which may be summarized as 
to origins as follows: 
1. Mexican—Central American region . . . 71 species 
la. Origin not further localized (including maize, beans and cacao) 
8 species 
1b. Northern Mexico and adjacent areas (sunflower and a pump- 
kin species) 4 species 
le. Central Mexico (amaranth, chia, Opuntia and a race of the 
avocado) 24 species 
id. Southern Mexico and lowland Central America (yam bean, 
indigo and papaya) 27 species 
le. Guatemalan highlands (lima bean, chayote and a race of the 
avocado) 8 species 
2. Andean area (cotton and tobacco) . . . . 6 species 
3. Brazil-Paraguay region (pineapple) . . . 8 species 
4. Uncertain (chile peppers and sweet potato) 8 species 
It will be noted that most of the Mexican cultivated 
plants are native to Middle America, but that some spe- 
cies have been received through diffusion from the An- 
dean area and from lowland South America. The data 
do not conflict with the hypothesis of several independent 
centers of origin for New World agriculture. The origin 
of agriculture as such is discussed and a gradual develop- 
ment through what may be termed a ‘‘commensal’”’ pat- 
tern is upheld. The botanical evidences concerning trans- 
Pacific cultural contact are briefly noted. It is felt that 
real progress is being made in the study of cultivated 
plants and that cooperation between different disciplines 
promises continued and valuable progress in the future. 
[ 160 ] 
