DATES OF EGYPT AND THE SUDAN. 9 
for a few exceptionally early sorts.!. This apparent discrepancy may 
be explained for United States localities by the frost terference in 
the spring and fall, while the Nile delta region is practically frostless ; 
the coast entirely so, while the Gizeh district is subject to rare and 
only light frosts. With frost immunity in autumn, the dates of the 
Egyptian maritime belt may hang on the trees, slowly maturing, even 
after the mean temperature falls below 64.4° F., as it does by the first 
to the middle of November. It must be remembered, too, that these 
dates do not mature upon the trees, but are cut and marketed in what 
is called a ‘‘hard ripe” condition, the sugar deposits being probably 
completed, but with the enzymic actions which promote the ripening 
not yet begun. 
This region, having a mean temperature of 70° F. from February 
to October, inclusive, does not produce packing dates at all. The 
Amri, the one important packing date of the delta, is produced at Sali- 
hieh, Korain, Fakus, and a few at Birket el Hadji, all points in the 
margin of the delta lands bordering on areas of bare desert sands. ~ 
(PI. III, fig. 1.) Manshia, on the margin of the delta, a few miles north 
of the Gizeh Pyramids, where considerable quantities of both Amhat 
and Siwah dates are cured, has a climate so influenced by the proximity 
of the Libyan Desert that it should be considered under the same cate- 
gory. The record of Abbasia, the suburb of Cairo on the rocky slopes 
of the naked hills to the northeast of the city, may be taken as most 
nearly representative of these border localities, especially of Birket el 
Hadji and Manshia. Here (Table 1) the mean for the year is but a 
fraction below 70°, that for the growing months of February to Octo- 
ber being 73.68°; and the summation of heat units from May to Octo- 
ber is 2,714. An incomplete record for Ismailia,? on the Suez Canal 
about 25 and 30 miles southeast of Salihieh and Korain, agrees within 
an average of 1° in the monthly means with the records of Abbasia 
and gives an almost identical summation of heat units above 64.4°. 
The mean relative humidity is between that of Abbasia and that of 
Heluan, but with less fluctuation than either. 
Even with the additional heat afforded by these localities on the 
desert border, the dates are pulled from the stems in an immature 
‘“‘hard ripe” condition, and the ripening is completed in drying yards, 
preferably on floors of coarse pebbles to reflect the heat. 
Tt is from such higher temperature conditions at Birket el Hadji, 
where their groves border the sand hills toward the open Arabian 
1 Thomas H. Kearney, on pages 20 and 21 of Bulletin 92 of the Bureau of Plant Industry, entitled ‘“ Date 
Varieties and Date Culture in Tunis,” shows that at Susa on the Mediterranean coast, 120 miles north of 
Gabes, two varieties of dates are grown where the summation of heat units is probably less than that of 
Sfax (1,968° F.). These are, however, varieties of inferior quality and the fruit keeps but a short time 
after gathering. 
2 Lyons, H. G., Physiography of the Nile River and Its Basin, 411 p., 48 pl. Cairo, 1906. 
96613° Bull 271—15-—_? 
