40 BULLETIN 271,, U. S. DEPARTMENT OF AGRICULTURE. 



of more than 15 degrees and, equally important, a range in the per- 

 centage of mean relative humidity varying from 74 per cent at Port 

 Said to only 24 per cent in Dongola Province in the Sudan. 



For convenience in study, the region has been divided into three 

 zones, designated as (1) the maritime subtropical, comprising the 

 Nile delta below Cairo; (2) the desert subtropical, comprising the 

 Nile Valley from Cairo to Aswan and the western oases; and (3) the 

 desert tropical, comprising the date-growing sections of the Nile 

 Valley from Aswan to Khartum. The records of 12 Egyptian and 

 Sudan weather stations have been compiled and arranged in a table, 

 showing their bearing on date requirements. 



The characteristic date varieties of each zone are grouped to show 

 the influence of these varying climatic conditions and the important 

 facts brought out: (1) That the cool and humid maritime zone pro- 

 duces few packing dates, but almost exclusively those used in the 

 fresh, or "rutab," state; (2) that packing dates of superior quality 

 are produced in the moderately hot and dry portions of the desert 

 subtropical zone; (3) that the hotter, less humid portion of the desert 

 subtropical zone and the desert tropical zone produce almost ex- 

 clusively the hard, dry, self-cured dates, so easy of storage and 

 transportation and so important a part of the diet of the Arab people. 



The correct names of two varieties listed in the early importations 

 from Egypt as "Birket el Haggi" and "Oga de Bedrichen," promis- 

 ing in Arizona and California, were ascertained by visits to their 

 original localities. 



The identity of the date of which Mr. David Fairchild purchased 

 the fruit as a Wahi" in Fayum in 1901, with the Saidy, the great 

 packing date of the western oases, was learned on a trip to Khargeh 

 and Dakhleh. 



The Ibrimi and Sukkoti varieties of earlier published lists were 

 found to be synonyms of Barakawi, the dry date of greatest com- 

 mercial importance in the Sudan, probably originating in Sukkot. 



Of the 22 varieties of dates described, 14 have not been previously 

 published, and of the remaining 8 the descriptions are more complete 

 and are believed to be more accurate than any heretofore published. 



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