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 (191 2). 

 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. 



The Kansas State Water Survey has made use 

 of a device for shipping iced samples which has given 

 excellent results. The outfit is described in the Amer- 

 ican Journal of Public Health for May, 19 14, and 

 consists essentially of an insulated container in which 

 the bottles are firmly held by a simple mechanism. 

 With proper icing the samples are maintained at a tem- 

 perature below 10 degrees C. for two or three days 

 or even more. Very little change due to storage is 

 found in the counts on agar when plates arc incubated 

 at 37 degrees C. and in winter the 20-degree counts 

 are satisfactory on agar. Gelatine counts were found 

 to be erratic and not dependable. 



The following tables kindly sent us by Prof. C. C. 

 Young show the comparative numbers obtained in the 

 laboratory after certain periods of storage, and in 

 the laboratory as compared with the actual field 

 analyses. 



