394 BOTANICAL GAZETTE [JUNE 
especially the presence of invertase, and probably limitations in the 
distribution of the same, are more potent in determining the relative 
proportion of the sugars than the factors mentioned by LINDET. 
According to observations on the date, it seems that fruits of the same 
species but of different chemical nature are true chemical mutants, 
determined by the plant itself rather than by its environment. Fur- 
ther investigations may reveal cane sugar varieties of what BUIGNET* 
considered inverts ugar fruits, as grapes, currants, and figs, or invert 
varieties, among the partially cane sugar fruits, bananas, apricots, 
peaches, plums, apples, and pears. 
SLADE,’ basing a classification on the analyses of varieties, from 
the Tempe orchard, of various native seedlings and of native fruits 
from Mexico, divided dates into two main classes: cane sugar dates, 
embracing the Deglet Noor, and M’Kentichi Degla; and invert sugar 
dates, embracing Rhars, native seedlings, Mexican dates, and most 
others. It is possible to have partial cane sugar dates, and such do 
exist, as I shall point out later. While SLApr’s classification is correct 
for mature and cured dates, nevertheless all dates are decidedly of the 
cane sugar type at some time of their life-history.° This fact gave the 
first clue to the influence of invertase in determining the saccharine 
character of the date and probably of most other fruits. 
It appears probable that the carbohydrates may enter the fruit as 
cane sugar, for nearly all fruits, either cane or invert sugar, show an 
appreciable percentage of cane sugar at the period of maximum accu- 
mulation of dry matter. This is often very inconsiderable, as we see 
in Kerw’s? analysis of ripening cherries, and may not be detected at 
all, as in the ripening persimmon.* Even in these cases more cane 
sugar would be found if special precautions were taken to destroy the 
invertase immediately after removing from the tree. The cane sugar 
of the date vanishes very rapidly in the invert varieties. MuIRAN° 
+ Compt. Rend. 51:894. 1860; through Bull. 94, Bur. of Chem., U.S. Dept. Agric. 
$ All notes on the unfinished work with dates of H. B. SrapE (died June 5, 1995) 
were turned over to the writer and acknowledgment is made in this papeT stasis? 
material from that source has been used. 
6 Ann. Rep. Arizona Agr. Exp. Sta. 1'7:164, 165. 
7 Zeit. Anal. Chem. 30:401. 1891. 
8 BicELow, Gore, and Howarp. Jour. Am. Chem. Soc. 28:688. 
9 Chem. Zeit. 56:1003, 1021, 1283. 1893. 
