OBSERVATIONS OX THE DATE. 261 



hortoiu as minute reddish brown granules wliieh ean be sep- 

 arated mechanically in a fair state of purity. They are com- 

 posed, presumably, of the insoluble tannin, but, unless the dates 

 are very fresh, no longer give the tannin reaction even after 

 boiling with acids. It is believed that the tannin in the per- 

 simmon is distributed in the green stages throughout the fruit 

 and that on ripening it segregates into specialized tannin cells. 

 There it becomes insoluble and consequently the puckery taste 

 disappears. This is also true of the date, excepting that the 

 tannin is confined in all stages to the narrow zone of giant cells 

 where it is originally formed, and no segregation takes place. 

 The rats at the Tempe orchard discovered this also, for they 

 found tliat the outer shell of a green date was edible down to 

 this layer. Dates with lialf their skins eaten away mature nor- 

 mally. l>nt had it not been for this protecting layer the seed 

 M'ould undoubtedly have been injured. 



The development of the fruit takes place in three stages. 

 After fertilization very little change in the fruit itself can be 

 observed for several weeks, but during this period the entire 

 energy seems to be expended in building a long massive stem. 

 When this is nearly completed, the fruit starts to grow and the 

 seed to mature. When the fruit has reached its full size, but 

 is still green, it corresponds very closely in chemical character 

 to any other non-starchy fruit, and contains about 20% of dry 

 matter. The third staiie now begins and additional sugar is 

 heaped into the fruit at a rapid rate without any apparent change 

 in size until uj) wards of 00% dry matter is present. It rheu 

 softens, the tannin becomes insoluble Avith consequent loss of 

 astringency, and the fruit is ripe. The writer has recently shown 

 that for theoretical considerations this sugar probably enters 

 the fruit as maltose, but is very rapidly converted into cane 

 sugar which in certain varieties, as Deglet ISToor and M'Ken- 

 tichie Degla, remains cane sugar, but in Rhars, Birket el Haggi, 

 Amari, Amreeyah and other varieties is converted by contact 

 with invertase into invert sugar. They all contain invertase suf- 

 ficient to change manv times their weight of cane susi-ar to in- 



