DESCRIPTION OF AN APPARATUS FOR OBTAINING 



SAMPLES OF WATER AT DIFFERENT DEPTHS 



FOR BACTERIOLOGICAL ANALYSIS 



FRANK C. WILSON 



From the Biological Laboratory of the Wisconsin Geological and Natural History 

 Survey, Madison, Wisconsin 



Received for publication October 23, 1919 



A number of years ago a biological survey of the waters of Lake 

 Mendota, Wisconsin, was begun by the Wisconsin Geological 

 and Natural History Survey. In this survey it was planned to 

 include a study of the number and types of bacteria. The sam- 

 ples were to be taken at various depths and in all sorts of weather. 

 It was realized that an apparatus which would enable the analyst 

 to collect the samples with the least expenditure of time and 

 trouble would be a great aid in the work. 



A review of the literature shows that many forms of deep water 

 samplers have been used. In general these may be divided into 

 two groups: first, the vacuum bulb type; second, the bottle type 

 which consists of a bottle from which the stopper is lifted and 

 the water allowed to run in after the apparatus has been lowered 

 to the desired depth. 



The commonest type of the exhausted bulb sampler consists 

 of a thinly blown bulb such as a retort bulb. The bulb is par- 

 tially exhausted and sealed at the neck. By means of a mechan- 

 ical device the constricted neck is broken when the apparatus is 

 at the desired depth in the water and the sample of water allowed 

 to pass into the bulb. This type of sampler is unsatisfactory 

 because the bulb must be blown especially for the sampler. 

 Where a considerable number of samples are to be taken it would 

 be difficult to keep a supply of bulbs on hand. 



Another type of sampler used, consists of a metal frame-work 

 inclosing a bottle with a ground glass stopper (Abbott, 1915). 



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