FRESH-WATER ALG. 263 
slate of, Bilin, which supplies the tripoli used for 
polishing stones and metals, are all found, when 
subjected to the microscope, to consist almost en- 
tirely of the silicious plates of diatomacez, united 
together without any visible cement. The world, 
it has been well said, is a vast catacomb of dia- 
toms, a grand herbarium in which these most an- 
cient plants have been preserved in a state of 
completeness and accuracy little short of. their 
living perfection, to be to us the unimpeachable 
records of time, as it were, beyond time, of moun- 
tains and shores, rivers and seas, that seem myth- 
ical even to the geologist. They were at work 
Hiuan-Tsung of the great dynasty Tang, in the third year Tain- 
pao (744 after Christ), a spring in Wujin (now Liang-tschen-fu, in 
the province Kan-su), which ejected stones that could be prepared 
into bread, and were gathered and consumed by the poor. (Schott.) 
‘Under the Emperor Hian-Tsung of the same dynasty, in the 
ninth year of the period Yuen-ho (809 after Christ), the stones be- 
came soft and turned into bread. (Biot.) 
‘Under the Emperor Tschin-Tsung, of the dynasty Sung, in 
the fifth year of the period Ta-tschong-Tsiang-fu (1012 after 
Christ), in the fourth month, there was a famine in Tsy-tschen 
(now Ki-tschen in Ping-yang-fu, in the province Schan-si), when 
the mountains of Hiang-ning, a district of the third rank in the 
same part, produced a mineral fat (Stone-fat) resembling a dough, 
of which cakes could be made. (Schott.) 
‘Under Jin-Tsung, in the seventh year of the period Kia-yeu 
(1062), stone meal was found. 
‘Under Tschi-Tsung, in the third year of the period Yuen-fong 
(1080), the stones turned into meal. All these kinds of stone-meal 
were collected and consumed by the poor. (Biot.)’ 
. 1 As the earliest fossil diatoms yet found, judging from the 
figures of Ehrenberg, are identical in every point with the great 
