288 HEARINGS BEFORE COMMITTEE ON AGRICULTURE. 
The CHatrmMan. Are you not practically doing this work in some 
other way? 
Mr. Merriam. Not at all. It would do no good to see that grapes 
and oranges and raisin grapes would do on a particular kind of soil, 
if you found that soil in Maine, New Hampshire, or Connecticut. 
You have to know what belt that soil recrosses in order to know the 
variable areas. So, on the other hand, with hardy cereals and hardy 
apples, if you found soils like that on which they grow through the 
Southern States, it would be impossible, obviously impossible, to 
grow those crops there, because they are in a different life zone. 
entirely—in a belt in which they could not possibly thrive. 
The CHatrmMan. What is your method of determining that? 
Mr. Merriam. We determine the climatic belts which control the 
distribution of animal life and the growth of plants. We actually 
map the real distribution of animals and plants as they occur in nature, 
in a wild state, and then coordinate those areas with the climatic factors 
which govern them. We have found out that the northern limit of 
species of southern origin is determined by the activity of heat for 
ite season of growth and introduction. We have determined that the 
southern limit of southern species is determined by the hottest part 
of the summer; and I have maps here showing the actual temperature, 
and showing the extent of areas determined in that way, with the 
boundaries of the life zone as we have mapped them, from actual dis- 
tribution of species in the field. 
Mr. Scorr. What do these maps indicate? 
Mr. Merriam. They indicate the boundaries of the principal trans- 
continental belts that are fitted for large association of species that 
are not fit to thrive in other areas. They are based on the study of 
wild animals and plants in the field coordinate with temperature data, 
and are the natural agricultural belts. We are carrying this on in 
very much more detail than you see in these small-scale maps here. 
Mr. Lams. Have you one defining the cotton belt? 
Mr. Merriam. No; I have not, here. The cotton belt is a subdivi- 
sion of this austral riparian belt. 
Mr. Scorr. Do you publish a bulletin to go with this map? 
Mr. Merriam. Yes; giving a list of the ditferent varieties of apples, 
peaches, grapes, plums, cherries, and cereals of different kinds that 
thrive in each of these areas. That is our principal and most important 
work for agriculture. It means a great deal in a region which is 
developing fast agriculturally, like many parts of the far West, where 
it saves a man an absolute loss—as has occurred over and over again, 
year by year—in futile experimentation, to try to make things grow 
in areas where nature is not fitted for them. and where they can not 
be a commercial success. 
Mr. Grarr. Do you mean that the result of these investigations has 
a obtained principally by the habitat of the various animals and 
1ras ¢ 
Mr. Merriam. Certainly. Those are the main factors we have used; 
and these same areas have been found, as Doctor Howard has shown, 
to coincide with the areas over which noxious insects extend. When 
we haye an outbreak of some noxious insect it is in a natural home 
area, and in extending its range it will not pass the boundaries of its 
natural zone. So we can lay out beforehand the area where it will 
occur next year or the year after next, or the same year, in its exten- 
