OBTAINING WATER FOR BACTERIOLOGICAL ANALYSIS 107 



thus preventing contamination. With the small opening and 

 the bend in the filling tube, contamination of the sample is almost 

 impossible either from the water while the sample is being drawn 

 or from the air after it leaves the water. Several thorough tests 

 have been made with a tube which has the tip seal broken. 

 Such a tube was lowered to 22 meters in the water and pulled 

 rapidly up and down in an attempt to force water in, but when 

 the apparatus was drawn up there was no water in* the sample 

 tube and only a drop in the tip of the filling tube. We may there- 

 fore be sure that samples collected in this way contain only the 

 organisms from the water at the desired depths. 



The use of one line to lower the apparatus and to break the 

 seal is a decided advantage which the majority of samplers do 

 not possess. The greatest inconvenience we have found with 

 this sampler is the preparation of the tubes. It requires time to 

 prepare the tubes and unless they are handled carefully the tips 

 are easily broken. 



In the work on Lake Mendota this sampler has only been used 

 to a depth of 23 meters, but without doubt it could be used to a 

 much greater depth without any influence of hydrostatic pres- 

 sure. Its use indicates that it is safe up to a depth of 23 meters. 



SUMMARY 



In this article there has been described a bacteriological water 

 sampler, together with the method for its use. This sampler 

 furnishes a convenient and rapid means for drawing samples of 

 lake water for bacteriological analysis. 



REFERENCES 



Abbott, A. C. 1915 Principles of Bacteriology. Philadelphia, 617. 



Bertel, Rudolf 1912 Ein einfacher Apparat zur Wassererentnahme aus be- 



liebigen Meerestiefen fur bakteriologische Untersuchungen. Central- 



bl. Bakt., Abt. II, 33, 389. Original Biolog. Zentralbl., 31, 1911, 58-61. 

 Bessgn, A. 1913 Practical Bacteriology, Microbiology and Serum Therapy. 



London, 852. 

 Esmarch, E. von 1895 Quoted by Draer, A. Das Pregelwasser in Bakteriolog. 



u. Chem. Beziehung. Zeit. f. Hyg., 20, 339-341. 



