50 ELEMENTS OF WATER BACTERIOLOGY 



rotating the tube until the medium has solidified in a 

 thin layer on the inner wall. Other bacteriologists 

 have devised ingenious field kits for adapting the plate 

 method to this purpose, of which one very good form 

 has recently been described by Van Buskirk (1912). 

 The opportunity for air infection in work done outside 

 a proper laboratory is, however, always great; and it 

 is almost impossible to secure proper conditions for 

 incubation in any makeshift establishment. On the 

 whole, the authors are of the opinion that laboratory 

 examinations are to be preferred to those made in the 

 field, if a laboratory can be reached within 12 hours 

 or so of the time of collection of the samples. 



