8 
IOWA ACADEMY OF SCIENCES. 
upon the inner compartment of the pail which contains 
the dish rack. Also a flat lid fits over the entire pail. The 
bail is fastened to two small open tubes that project from 
the side of the pail a little distance below the top of the 
inner compartment. The outside of the pail is covered 
with asbestos paper or felt. 
For work in the field it is necessary to carry a small bag 
containing tubes of gelatine and agar, a cylinder of pipettes, 
an alcohol lamp, collecting bottles and perhaps a small tin 
can. The outer compartment of the pail is packed with 
broken ice. The sterilized Petri dishes are placed in the 
rack. Upon collecting the water the plates are poured and 
are at once replaced in the rack where the gelatine very 
quickly solidifies. A small hand level may be used for 
leveling the pail by placing it upon the flat lid; the pail be- 
ing blocked up with sticks or anything convenient. The 
gelatine will now have an equal depth in all parts of the 
dish. The plated samples may then be taken to the labora- 
tory at the leisure of the worker, he knowing there will be 
no multiplication of bacteria or diminution of numbers. 
The apparatus is primarily for use in warm weather but 
will be found convenient for cooler weather also. It may 
be used in the laboratory for solidifying plates, if there is 
no ice box convenient, by turning a stream of cold water 
into the outer compartment. The water does not get into 
the inner compartment because the outlet tubes are at a 
lower level than the top of the compartment. . The pail 
may be made for six, twelve, or more dishes, as seems most 
desirable. 
