SPECIAL EXAMINATIONS 347 



sewage pollution, but easily found if present. Such an 

 organism is Bacillus coli communis, which is presentlin 

 enormous numbers in the sewage of man and animals ; 

 and is therefore likely to be present in sewage contamin- 

 ated water, even after great dilution. The B. coli is 

 also a more resistant organism than the dangerous forms, 

 and so serves to indicate pollution at a later stage than 

 these could possibly be found in a water. So far it is not 

 possible to distinguish B. coli of human origin from those 

 of animal origin. It is stated that those of human origin 

 are more pathogenic to animals. 



There are various methods in use in this country. A 

 Committee of the Royal Institute of Public Health 

 appointed to consider the " Bacterioscopic Examination of 

 Water," reported in 1904 (Journal of State Medicine, vol. 

 xii, p. 471) as follm 



Minimal Procedure. Unanimous^yeport : 



(a.) Enumeration of bacteria pffesent in_a-water 

 sample, capable of growing on a medium incubated 

 at room temperature (i8-22 C.). 



(b.) Search for Bacillus coli, and identification 

 and enumeration of this organism, if present. 

 Majority also recommended : 



(c.) Enumeration of bacteria present in sample 

 capable of growing on a medium incubated at blood 

 heat (36- 3 8 C.). 



(d.) Search for and enumeration of streptococci. 

 (e.) Do not recommend routine examination for 

 Bacillus enteritidis sporogenes ; but in exceptional 

 and special cases advise that it be searched for. 



They further report on mode of collection of sample, 

 media to be used in the tests, etc., of which the following 

 is a brief summary : 



Collection of Sample. The sample should be collected in 

 sterile stoppered glass bottles (minimum quantity 60 c.c., or 

 2 ounces), and should be packed in ice. At least 10 ounces 

 of sample should be sent, and its examination should be begun 

 within three hours, or it should be left packed in ice. 



Enumeration of Bacteria. The media to be used are all to 

 be standardized to have a reaction of +10 (Eyre's scale). 

 Owing to changes in reaction, media should not be more than 



