274 Trans. Acad. Sci. of St. Louis. 
Series A. This represents the results of a steamboat trip 
which was made Aug. 2,1900. The samples were plated 
immediately after collection. They were surrounded by ice 
and transported to the laboratory where they were placed in 
the ice box next to the ice. They were replated on the next 
day. 
Series B. Steamboat trip Aug. 16, 1900. Samples plated 
on the boat and again on the following day. The samples 
were kept on ice until plated the second time. 
Series C’. Steamboat trip Aug 30, 1900. The samples 
were plated on the boat immediately after collection and 
again on the next day. Care was taken to keep samples near 
the freezing-point by packing in ice. 
It is to be noticed in this series that at certain places two 
separate samples were taken, one deep and the other near the 
surface of the water. In all of these samples B. coli com- 
munis was found. 
Series D. Steamboat trip September 20, 1900. Samples 
were plated on the boat, were packed and kept in ice until 
. replated on the next day. 
From this table it will be noticed that the numbers of bac- 
teria at the second plating had in most cases not increased 
and in fact there was in certain instances a decided numerical 
decrease. 
It was also desirable to know what effect the immediate 
chilling of a sample would have on the number of bacteria. 
A few of the results of an effort to determine this are font 
lected in the following table : — 
