IOWA ACADEMY OF SCIENCES. 



PRELIMINARY REPORT ON THE DIATOMS OF 

 IO^A^A. 



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 diatomacesB 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.— Thej 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 



