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 eifect 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 col- 

 lected in the f ollowinsf table : — 



