304 REPORT OF THE CONFERENCE ON GENETICS. 
used for truck crops and other purposes, the orchardists who were not 
entirely discouraged going farther south to begin over again. Mr. Walter 
T. Swingle and Dr. Herbert J. Webber then set to work to obtain resistant 
varieties by crossing choice oranges and other citrous fruits sensitive to frost 
with the extremely hardy Citrus trifoliata, which stands the winters well - 
as far north as Washington,* and is occasionally cultivated as far north 
as Philadelphia, but which bears a small bitter, worthless fruit. They 
obtained many seedlings as a result of these crosses.t As soon as these 
had reached a size sufficient to furnish wood for budding, they were cut 
to pieces and budded upon the branches of older trees, in order to hasten 
their fruiting. In this way from many of these plants fruits were 
obtained at an early date, 7.e. within three or four years. I saw and 
tasted many of these new fruits. Among the number, a dozen or more 
proved of much interest, the quality of the fruit in some cases being 
excellent. ‘The variations among the seedlings of these trees, the second 
generation from the hybrid, are expected to be even more promising. 
A large number of these plants were also found to be quite resistant 
to cold, so that when they could not be used for their fruits they were 
still available as hedge plants. Some of the citrous fruits thus obtained 
can undoubtedly be cultivated as far north as the Carolinas. 
Resistance to Alkali and to Drought.—The Department’s work on the 
production of “alkali ’’-resistant plants is still under progress. We have 
thousands of acres in our West which are capable of producing a great 
quantity of food for man and beast were it not for the fact that these 
lands are more or less permeated by harmful alkaline and neutral salts. 
Many of these districts are scantily supplied with rainfall, and are 
cultivated by means of irrigation, which sometimes washes out the alkali 
and at other times washes it in, as has been your own experience in 
Egypt. The problem was to find plants of agricultural importance which 
would grow on the best of these alkali lands. It was discovered that 
some plants, for instance, the date palm, will flourish in soils that contain 
so much alkali that ordinary plants cannot grow at all, and with this in 
mind Mr. Walter T. Swingle has made several trips to the Sahara, and 
has imported for the Department large numbers of such palms, which are 
now growing satisfactorily in several places in Arizona and California. 
Many of these palms have already fruited heavily, yielding dates of 
excellent quality, and there is not the slightest doubt but that we shall 
within a few years be growing our own dates—at least all of the finer 
table varieties. 
The thought was that it might be possible also to find somewhere in 
the world alfalfa and other agricultural crops with a greater root 
resistance to alkaline water than that manifested by the ordinary varieties, 
the cultivation of which on these lands had failed. With this end in 
view, the Department sent out explorers to various parts of the Old 
World and also into our own alkaline tracts, the result being the 
discovery that there are certain types of leguminous and other plants 
* During the last twenty years I recall only one winter in which it was at all 
injured. 
+ See Dr. Webber’s paper in the Report of the Hybrid Conference, 1899, p. 128 
et seq.— Ep. 
