178 MICROBIOLOGY 



able for infection, if individuals suffering with intestinal dis- 

 ease are present on the water shed. There seems to be no rule 

 that can be followed for interpreting the findings generally, as 

 each case must be determined on its merits. 



In water analysis it is often necessary to determine the 

 presence or absence of organisms detrimental to the water 

 other than the cause of specific diseases. The veterinarian is 

 interested in water analysis largely from the "disease pro- 

 ducing" point of view and consequently he is most anxious 

 about the presence of pathogenic bacteria or those indicating 

 dangerous contamination. The work of Whipple is quite 

 helpful in determining the higher forms of life often found in 

 water. 



Fungi and animal parasites. In addition to disease pro- 

 ducing bacteria, many fungi and animal parasites gain en- 

 trance to the animal body through water. 



Purification of water. Water is purified by (1) sedi- 

 mentation, (2) filtration, (a) sand filters, (b) mechanical 

 filters, and (3) by filtering through ordinary filters to re- 

 move the dirt and boiling to destroy the bacteria. 



BACTERIOLOGY OF MILK. 



Bacteria in milk. It was formerly supposed tHat freshly 

 drawn milk was bacteria free. Bacteriological examinations 

 have proved, however, that it is practically impossible to ob- 

 tain milk free from bacteria. Leopold Schultz 1 was among 

 the first who carefully conducted experiments relative to bac- 

 teria in freshly drawn milk. He found that the fore-milk 

 usually contained numerous bacteria (97,200 per cc.) while 

 that taken near the middle of the milking contained many less 

 (9,000 per cc.) and milk drawn at the close contained com- 

 paratively few (500 to 600 per cc.). Gernhardt 2 investigated 

 this subject but obtained quite different results, in that he 

 found that the milk drawn at the close of milking often con- 

 tained enormous numbers of bacteria (7,000,000). He 



Schultz. Archiv f. Hygiene, Bd. XIV (1892). 

 Gernhardt. Inaug. Dis. Jurjew, 1893. 



