116 IOWA ACADEMY OF SCIENCES. 



Order Ricciace^. 



Bk'ckt frostii Aust. Not common on mud- flats on Muscatine 

 island in Louisa county. 



R. lutescens Schwein. Very common on mud-flats on the 

 Mississippi bottoms below Davenport, and on Muscatine island 

 in Louisa county. 



B. flultans L. Common in ponds and on mud at Cedar 

 Rapids, Forest City, near Davenport, and on Muscatine island 

 in Louisa county. Also in Emmet county {11. I. ('ratty). 



A SIMPLE INCUBATOR. 



BY L. S. ROSS. 



No claim of originality is made in the presentation of 

 the description of the simple apparatus used by me as an incu- 

 bator. The idea, so far as I know, originated in the mind 

 of Mr. W. D. Frost, assistant instructor in bacteriology in 

 the University of Wisconsin. 



The incubator consists of a drygoods box, lined inside and out 

 with asbestos paper, set on a galvanized iron base, and divided 

 by wire netting into a convenient number of shelves. Heat is 

 obtained from a rose burner, and is regulated by a thermostat 

 made in the laboratory. The box I used is thirty-three inches 

 long, nineteen inches wide and twenty-six inches from front to 

 back. The cracks were stopped with rags and then the asbestos 

 paper was pasted on the w^ood. A door was cut in the front, a 

 window in one side and one in the door. The door is 25x13 

 inches; the side window is 9x8 inches, and the one in the door 

 is 12x6 inches. A galvanized iron pipe, three inches in 

 diameter, open at the lower end and closed or opened at 

 the top by a circular cut-ofl", passes through the box from the 

 base and projects six inches above the top. A hole, three and 

 one-half inches in diameter, is cut through the center of the 

 lower end of the box and the iron base, leaving only one thick- 

 ness of asbestos paper between the chamber containing the 

 burner and the lower compartment of the incubator. This hole 

 may be closed by a galvanized iron slide. The incubator 

 is divided into three compartments, the lower two of which are 



