279 
ON THE FORMATION OF OOLITE.* 
By Dr. A. Rothpletz, of Munich. 
On the low shore of the Great Salt lake in Utah, there lie be- 
tween the pebbles and sand-grains, in great multitudes, snow- 
white calcareous corpuscles. They are thrown on the smooth 
strand by the waves of the lake and form a substantial part of 
the beach-sand. Where they still lie in the water, we usually 
see them partly covered with a bluish-green alga-mass. 
I could take with me last fall only dry material of this alga ; 
but that sufficed perfectly to recognize that the algoid bodies con- 
sisted of colonies of Ghrocapsa and GlctotJifcc cells, which richly 
secrete carbonate of lime. 
The cells of the Glmocapsa are 2 // in diameter and spherical, 
those of Uhrotliccc 2 — 3 // thick and 4 — 5 y. long. 
They are invested with a clear, transparent, jelly-like mem- 
brane, which exceeds the cells in thickness. There are often 
several cells in one membrane, and the more or less spherical 
membranes are always pressed closely together, creating nearly 
the appearance of a uniform mass of jelly. 
The lime is enclosed in the alga-body in the form of rounded 
tubercles which often mass themselves together into larger, irreg- 
ular tubercular Ijodies. It is a fine-grained aggregate of calcite 
which always incloses numerous dead alga-cells that have already 
lost their greenish coloring. 
The snow-white and partly silver-gi-ay calcareous bodies of the 
strand are of three-fold form: first, there are irregular tubercular 
bodies attaining several millimeters in diameter, second, spherical 
or oval forms for the most part one-third of a millimeter in diam- 
eter, and, third, long, thin rods about one-half a millimeter long 
and one-tenth of a millimeter broad. 
If we dissolve these bodies in dilute acid, the dead and shriv- 
eled fission-algse become free in quite the same way as by dissolv- 
ing the lime of the living algtt. The snow-white, calcareous 
bodies may, therefore, be understood as dead alga-bodies. 
The rounded to oval forms are, indeed, both b}' their external 
form and b}' the microscopic arrangement of the calcite, true 
Oolites. Around an inner nucleus of irregularly granular lime, 
are laid concentric shells with, at the same time, radial arrange- 
* From the Botanisches Centralblatt, Nr. 35, 1892. Translated by F. W. 
Cragin. 
