Over the past two weeks, I have been puzzling over a strange organism which I
found in a freshwater sample. I rpovide a description below and would greatly
appreciate any help in identifying this organism.
Description of Unknown Entity
In examining a sample taken from a roadside ditch which was rich in
algae, I noticed, several weeks later, an odd entity at the bottom of the
sample. I am assuming (with little justification) that it is some sort of
alga. The key characteristics which I have been able to discern thus far are:
1) It is found in freshwater.
2) It is shaped like a miniature volcano and is calcareous.
3) The "cone" of a typical organism is about 180 microns in diameter and
extends upwards perhaps 40-50 microns.
4) The cone of the organism is highly birefringent and produces a striking
Maltese cross under crossed polars.
5) The cone dissolves immediately in 10% HCl and slowly and observably in 1%
acetic acid. When observing the rounded peak of the cone, there appear
to be projections which at first glace looked like sand grains.
However, when treated with acid, they too dissolved.
6) When treated with Methyl Green Acetic, the cone slowly idssolves and what
remains is a disk-shaped layer which takes up the stain. The organic
disk shows very little in the way of differentiation or even much to
suggest cell structure.
7) The underside of the cone is hollow.
8) The crystals along the edge are very minute and densely packed to give an
almost feathery appearance.
9) A significant number ofthe specimens look like two of the cones have fused
and that there is a line of connection between the two halves; in other
words, it appears as though the organism is dividing.
10) It is no uncommon to find clumps of the organisms consisting of six,
eight, or even more joined together in irregular patterns.
11) After dissolving the calcareous cone, I treated the remaining disk with
Acridine Orange. There were many very samll points of typically bright
light green fluorescence, but no discernible larger structure nor any
apparent patterns among the points.
I have checked a variety of references and have been unalbe to find any
references to calcareous freshwater algae, except for the mentions of lime
structures in genera such as *Chara*. If anyone can provide any suggestions
about what this creature might be or where I might look to get further
information, I would be most grateful.
E-Mail: HOWEY at UWYO.EDU
Richard L. Howey
University of Wyoming
P. O. Box 3392
Laramie, WY 82071