THE AVOCADO IN GUATEMALA. 9 
Material on which to base a classification has been somewhat in- 
adequate in the United States. Hence it has been thought that when 
the great avocado regions of tropical America came to be explored 
groups or races not yet known in the United States might be dis- 
covered. A canvass of the avocado-producing regions of Guatemala, 
however, has failed to bring to light any new groups, the investiga- 
tions tending only to confirm the classification already in use in the 
United States. Mexico, with its vastly greater area of territory, 
may perhaps yield groups as yet unknown to horticulturists, but no 
critical study of the avocados of that country has yet been undertaken. 
Perhaps the horticultural groups have been derived from distinct 
species of Persea. If not, they have at least become differentiated 
through the accumulation of variations during a long period of 
cultivation under different environmental conditions. In order to 
determine their exact status it becomes highly desirable to locate the 
wild prototype of each, if such a wild prototype still exists. This 
has not yet been done by anyone having in mind the classification of 
trie' cultivated avocados. The task is made difficult by the fact that 
the southern Mexican and Central American region, where the wild 
prototypes are probably to be sought, has been the scene of intense 
agricultural activity for centuries. The primitive forest has been 
leveled to the ground to make way for maize fields; the maize fields 
have been abandoned, the inhabitants of the region have emigrated 
to other parts, and the forest has again taken possession. After a 
period new peoples have arrived upon the scene, and the process has 
been repeated. This is indicated by archaeological remains in many 
parts of this region. 
Under these conditions the wild species from which our cultivated 
avocados are derived may have disappeared, and, on the other hand, 
trees which are found in the forest at the present day and have every 
appearance of being indigenous may have been placed there by the 
hand of man. 
Lacking exact knowledge of the wild prototypes of these culti- 
vated races, a comparison of the most primitive forms which can 
be found at present will bring out more racial characters^ or at least 
emphasize existing ones more strongly, than will a comparison of the 
highly developed varieties found in cultivation, for cultivation tends 
to conceal the racial characters by bringing the various races to a 
common level. Thus, the exceedingly thick and hard outer covering 
of the fruit which is typical of the Guatemalan race and conspicu- 
ously present in the primitive avocados of Alta Vera Paz becomes 
thinner in many of the cultivated varieties and closely approaches 
the skin of the West Indian race in character. The fruit increases 
vastly in size, assumes various shapes, and the seed becomes propor- 
tionately smaller. Since cultivation tends to work the same changes 
