Formation of Oolite. — Rothpletz. 281 
grains which cohere in thin pellicles, and have quite the aspect 
of the tission-alga?, as they occur in the Utah oolites. 
I liave made the attempt to prove the plant-nature of these 
surviving pellicles by treatment with sulphuric acid and iodine 
solution, as well as with chloriodide of zinc, and thereby gained 
the knowledge that no blue coloring, but, indeed, a j-ellowish 
brown coloring, took place. Thus, however, behaved the fission- 
algae of the Salt lake and, to my astonishment, it was quite im- 
possible for me to color, in this waj^ the cell-membranes of a 
Halimeda which I had collected in the Red sea. 
It appears thus that the incapacity of cellulose to be stained 
blue, occurs not only in the Fungi but also in the lower Algae. 
The oolites of the Quaternary deposits and those of the drift- 
sand are all, without exception, porcelain-white. Among those, 
on the contrary, which I have collected at Suez, on the strand ac- 
cessible only at ebb tide, I found a smaller number which have a 
silver-gray to greenish-blue color and are not easily to be dis- 
tinguished from the silver-gray oijlites of the Salt lake, if there 
were not the inner foreign sand-grain. 
The explanation of the inner vermiform canals, the study of 
the fresh-water fission-algae furnished me. "Where these live in 
great abundance in damp places, springs, or pools, there lime- 
secreting Ch roococci are accustomed to grow in a forest of thread- 
like fission-algae. So also may the case be in the sea. The 
thread-like algae may then become encased by the lime-crusts, 
their room may later be filled up with lime, and thus they con- 
tinue to preserve their external form. 1 suppose, therefore, in 
the vermiform structures of the Sinai oolites certain thread-like 
algi« which were of course not themselves immediateh' concerned 
in the 0()lite-formation, but by the company in which they lived 
were imprisoned with it. It will be the task of future dredging 
investigations to bring to light the living or)lite-maker from the 
depths of the Red sea. 
Eight years ago 1 found in the Lias of the Vilser Alps (in the 
so-called •' Aechsele" in the Reichenbacher valley) a gra}' lime- 
stone in a thickness of several meters, deposited between Ijrachio- 
pod-bearing white and coral-bearing limestone. The same was 
quite filled with little, longish corpuscles which, owing to their form, 
I regarded as organisms. The}' are rods \ mm. thick and up io 1 
mm. long, rounded oti' at both ends. In section, we recognize an in- 
