IOWA ACADEMY OP SCIENCES. 
47 
PRELIMINARY REPORT ON THE DIATOMS OF 
IOWA. 
BY P. C. MYERS. 
Within the last two years the author has often had occasion 
to congratulate himself for having acted on a suggestion from 
Prof. B. Shimek, of the State University of Iowa, to take up 
the study of a group of organisms which hitherto had, from 
the botanists of this state, received but scant attention. 
The diatomacem constitute a group of microscopic organ- 
isms hovering near the place of meeting, if such there be, of 
plants and animals. Their closest affinities, however, seem to 
be with the plants. 
Unicellular though they be, they make for themselves a 
glassy covering, whose two parts fit together as the top and 
bottom of a pill box. Chlorophyl is present, which, however, is 
masked by a brown coloring material called diatomin. Nearly 
all these little organisms have the power of movement; a 
graceful, gliding motion that reminds one of little steamboats. 
Their study is connected with considerable difficulty, which 
probably accounts for their being neglected. 
First . — They must be collected, a not o’er easy task. 
Second . — They must be cleaned, in which not less than seven 
separate and distinct operations are necessary; some of these 
are boiling in nitric acid, immersion in potassium permanganate 
for three or four days, boiling in hydrochloric acid and a 
deal of washing. 
Third . — They must be mounted, one at a time, on -separate 
slides. As these little objects range in size from one-fiftieth of 
an inch, in the largest, to one-two-thousand-five-hundred-for- 
tieth part of an inch in the smallest, it cannot be said to be 
heavy work, but it requires considerable concentration of the 
attention. 
Fourth . — They must be identified. As the literature is badly 
scattered, one cannot hope to do much without several expen- 
sive sets of books and pamphlets. Even then there is a little 
