CYTOLOGY—DATES 
solved. The visible stages in develop- 
ment have been observed and described 
ad infinitum. Both experimental cy- 
tology dealing largely with living ma- 
terial, and anatomical studies of thin 
sections, stained so as to show the most 
minute details of structure, are contribut- 
ing to the solution of the problem, but 
the fundamental underlying phenomena 
are still unknown and seem as difficult as 
the problem of life. The eggs of the sun- 
flower and the willow, like the eggs of 
flowering plants, are too small to be 
examined with the naked eye, but even 
when examined by the aid of modern 
technique and the most powerful micro- 
scopes, they present no essential differ- 
ence in external appearance, nor in ex- 
ternal structure, and yet one will al- 
ways develop into a willow, and the 
other into a sunflower. Within the fer- 
tilized egg are all the potentialities of 
the adult, even to the color of the flow- 
er, or the markings of the wings of the 
butterfly. 
“This view of Professor Chamberlain, 
is in substance supported by H. M. Ber- 
nard, an eminent French scientist, who 
in “Some Neglected Factors in Evolu- 
tion,’ published in 1911, outlines his 
work as follows: 
“"The cell, long considered to be the 
unit of organic structure, is here treat- 
ed as a form-feature of a fundamental 
network universally present in  pro- 
toplasmic tissues. The most primitive 
organisms are, essentially, living net- 
works from which all the tissues and 
organs of the higher animals and man 
have become differentiated, in response 
to an ever-widening range of environ- 
mental stimuli. 
““The periodic rise in the level of or- 
ganic life through the appearance of new 
types of animals, which the Darwinian 
theory of variation does not explain, is 
attributed to a series of units of struc- 
ture, starting with one simpler than the 
eell. Each of these units in turn, by 
colony-formation, has succeeded in pro- 
ducing an organism of a more complicated 
type, and has thus inaugurated a new 
and higher evolutionary period. In man, 
879 
the unit of the present period, the build- 
er of human societies, the psychical func- 
tions of the organic living network, latent 
in former periods, have been developed by 
interplay with a psychical environment. 
The mental development of man and the 
complicated problems of social life are 
thus treated as being serial with the 
simpler phenomena of organic life and as 
pointing to some future higher develop- 
ment of the great Cosmic Rhythm.’”’ 
See Floral Section. 
Dates 
Phoenix dactylifera 
The dates of commerce are the fruit of 
a species of palm, a tree which ranges 
from the Canary islands through North- 
ern Africa and the southeast of Asia to 
India. It has been cultivated and much 
prized through most of these regions 
from the remotest antiquity. Its culti- 
vation and use are described on the 
mural tablets of the ancient Assyrians. 
In Arabia, it is the chief source of na- 
tional wealth, and its fruit forms the 
staple article of food in that country. 
The tree has also been introduced along 
the Mediterranean shores of Europe; but 
as its fruit does not ripen as far north, 
the European plants are used only to 
supply leaves for the festival of Palm 
Sunday among Christians, and for the 
celebration of the Passover by the Jews. 
The date palm is a beautiful tree, grow- 
ing to a height of from 60 to 80 feet, 
and its stem, which is strongly marked 
with old leaf scars, terminates in a 
crown of shining pinnate leaves. The 
flowers spring in branching spadices from 
the axils of the leaves, and as the trees 
are unisexual it is necessary in culti- 
vation to fertilize the female flowers by 
artificial means. The fruit is oblong, 
fleshy and contains one very hard seed 
which is deeply furrowed on the inside. 
The fruit varies much in color, size and 
quality, under cultivation. Those who 
only know the date palm from the dried 
specimens of that fruit shown beneath 
a label in shop windows, can hardly im- 
agine how delicious it is when eaten fresh 
in Central Arabia. The dried fruit used 
DATILIA. 
