ABSTRACTS 119 



in the distinguishing characteristics of the streptococci of the bovine 

 type during the course of the corresponding experimental udder in- 

 fections. 



It is interesting to note that under experimental conditions the 

 quarters of a cow's udder are apparently separate as regards infection, 

 hence an examination of the milk from each quarter of the udder is 

 necessary before a mastitis can be excluded in the case of a suspected 

 cow. 



Bacterial Changes in Uniced Specimens of Water. Henry Albert, 



Jack J. Hinman, Jr., and Gharrett Jordan. 



It is well-known that bacteria tend to multiply rather rapidly in 

 water allowed to remain at ordinary room temperature. The purpose 

 of this investigation was to determine to what extent reliance may be 

 placed on bacteriological examinations of water sent to a distant 

 laboratory. 



Examinations of forty different specimens of water of various degrees 

 of purity, were made immediately after collection and again at the end 

 of 8, 24, 48, and 72 hours. The standard methods of the A. P. H. A. 

 were followed. 



The following conclusions regarding the bacteriological findings are 

 based on data obtained by a sanitary survey and by both chemical 

 and bacteriological examinations: 



1. The usual limit of 100 per cubic centimeter as the total number of 

 bacteria on standard agar plates at 20°C. may fau'ly apply to uniced 

 samples of water if examined within 8 hours after collection.. 



2. When uniced opecimens of water are not examined until 24 hours 

 after collection, the total number of bacteria at 20°C. which may be 

 permitted in ''safe" water may be placed at 200 per cubic centimeter 

 and if not examined until 48 to 72 hours after collection, at 500 per 

 cubic centimeter. 



3. The presence of as many as 50 bacteria per cubic centimeter on 

 standard Htmus lactose agar at 37°C. should throw suspicion on water 

 examined within 8 hours after collection although a total of 100 may be 

 permitted if not examined until 48 hours after collection. 



4. The presence of bacteria producing both acid colonies on standard 

 litmus lactose plates and gas in standard broth throws suspicion on the 

 water as polluted with sewage material, regardless of the length of time 

 that the water has stood after collection. 



5. The total number of bacteria in specimens of water which were 

 polluted with sewage material (or probably so) as determined by both 

 a sanitary survey and a chemical analysis is so high that it is not safe 

 to establish limits of bacterial counts. 



6. It is possible to depend on the results of bacteriological exami- 

 nations of uniced specimens of water in a large proportion of cases 

 provided the results are properly interpreted in the hght of the sanitary 

 survey, the chemical findings and the bacterial changes that occur in 

 such specimens of water. 



