THE FALL OF THE OLD EMPIRE. 455 
their desperate economic situation must in the very nature of the case have 
been reached at a different time at each city, giving rise to different closing 
dates in each, the extremes possibly covering a century, and thus conform- 
ing better than any of the other hypotheses with the chronological data 
actually found. 
This hypothesis also explains the greater salubrity and healthfulness 
of the climate in the southern Maya field during the Old Empire than at 
present, upon which Huntington lays such stress. For with the forest 
cleared from the immediate vicinities of the cities and the surrounding 
country under cultivation, less standing water would have collected, and the 
malarial mosquito would have occurred in far less abundance than in these 
same regions to-day, making the living conditions far more healthful than 
they are now. 
The writer has stated that every Old Empire city with which he is 
familiar is, or was when first discovered, covered with a luxuriant vegeta- 
tion, a dense tropical forest. Cook offers convincing evidence, both botanical 
and zoological, tending to show that these forests are not original primeval 
forests, but are examples of reforestation over previously cleared areas. 
“Reforestation can be traced through a succession of temporary types of 
vegetation, such as pines, oaks, Curatella, Acrocomia, Cecropia, Castilla, and 
Attalea. These are abundant in regions undergoing reforestation, but are ex- 
tremely rare in virgin forests or in those sufficiently old for tropical hardwood trees 
to have grown to maturity and occupied the land, along with their attendant hosts 
of epiphytes and shade-tolerant undergrowth. It thus becomes evident that many 
of the existing forests are not permanent or primeval, but show the intermediate 
stages of a process of reforestation which probably requires several centuries to 
reach a stable condition. ... . 
“Central America is the home of many species of the Chamzdorea, and other 
small palms which live among the undergrowth in the shady depths of the forests. 
Nevertheless many localities affording conditions apparently suitable for these 
palms are without any representatives of the group. The undergrowth palms re- 
main abundant only in regions which have not been completely deforested for 
agricultural purposes, and especially in districts too mountainous and broken for 
agricultural use.” 
His zoological evidence on this point is equally satisfactory: 
“Localities which contain remnants of ancient forests can be recognized by 
the presence of complete faunas of humus-inhabiting forest animals, such as the 
millipeds and centipeds, and some of the lower orders of insects and arachnids. In 
districts which are frequently cleared by cutting and burning many of the humus- 
inhabiting groups are exterminated. Even if they escape the fire they are unable 
to resist the exposure to the heat, sunlight, and dryness of cultivated lands. As 
long as the surface soil retains its humus and remains loose and pervious to water 
some of the smaller subterranean forms will persist, but when denudation is com- 
plete, or when the soil becomes sticky and impervious the humus-inhabiting types 
entirely disappear, as in many of the tenacious ‘gumbo’ soils of the Texas prairies. 
i alacant eS I TB ll AE ot a a CE Soll ea 
1 Cook, 1909, pp. 12, 13. 
