No. 385. THE ARID REGION. 
43 
It appears to me that throughout the arid region, where the 
sky is clear and the radiation great, the development of plants 
and insects 1s controlled largely by the distribution of frosts 
throughout the year. By a process of natural selection the 
native species (except such as are frost-proof) have learned not 
to appear or develop until the danger of frost is over. That 
this tardiness is not due to lack of warmth per se, is shown by 
the fact that introduced plants, such as the fruit trees, rush 
into bloom and get nipped in consequence. In the cloudy 
Seattle region it is very different. The climate is more uni- 
form, and there is much less danger of frosts following warm 
weather. Consequently, both bees and flowers appear early. 
The climate of the arid region is thus peculiar and presents 
a barrier to the ingress of plants and animals from without. 
For tropical and subtropical species the winters are too cold; 
for species of moist temperate regions the late frosts following 
warm spells are usually destructive. It is a curious anomaly 
that, in a locality having more than tropical summer tempera- 
tures, fruits of the temperate zone should fail on account of 
frost! 
Fortunately for the horticulturist, we already know many 
good late varieties of fruit trees, which escape even the latest 
frosts at Mesilla Park. But there can be no doubt that the 
true path to success will be that of selection, and the origina- 
tion of new and specially adapted varieties ; that is to say, man 
will have to imitate, in as short a while as he can, the process 
of nature in the case of the native productions. When he has 
accomplished this, he will reap the full benefit of the many 
excellent qualities of the climate, the dryness, sunshine and 
warmth, with moisture under control through a system of irri- 
gation. 
