LUTHER BURBANK 
kill if grown on the high plateaus of Wyoming. 
In general, it may be said that no region at 
higher altitude than about six thousand feet is 
adapted for fruit growing. 
In putting out catalogs of new fruit it is 
often desirable to state the minimum temperature 
that a new production will stand. I have done 
this, for example, in announcing my spineless cac- 
tus. As to average annual temperature, it may be 
convenient to recall that there is likely to be a 
mean annual difference of three degrees for each 
hundred miles of latitude. Thus, for example, the 
mean temperature at the southern line of Iowa 
will be found to be about three degrees lower than 
the mean temperature at the northern line; and 
this difference might, in case of a given fruit, make 
it folly to plant in northern Iowa a fruit that might 
live in the southern part of the state. 
As already pointed out, however, one of the 
main objects of the plant developer today is to 
produce hardy varieties, and doubtless it will be 
possible in the future to grow most varieties of or- 
chard fruits in regions that are now regarded as 
lying wholly beyond the northern limits of their 
possible culture. 
Stupyinc YouR MARKET 
Of course the proximity of the market is an 
item cf chief importance. Yet the experience of 
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