THE MICROBES OF WATER 291 



possible, for it has been proved by Dr. T. Leone, 1 

 Dr. P. F. Frankland, 2 and others, that microbes 

 multiply very rapidly in water. For instance, 

 Leone gives the following figures, which show the 

 rapid increase of microbes in a sample of water kept 

 for only five days : 



Number of Microbes in 1 cc. of water (at 14 to 18 (7.). 



Water on day of collection, . 5 



after 1 day's standing . . 100 



2 days' , . 10,500 



3 ... 67,000 



4 . . . 315,000 



5 ; . . 500,000 



If the water has to be transmitted a considerable 

 distance, occupying several days in transit, Dr. P. 

 Miquel 3 recommends the use of a glaciere, or box, 

 in which the bottle is surrounded with ice. 



There are two principal methods in use for the 

 bacteriological examination of water. The first is 

 the plate-cultivation process, which consists in 

 taking a known quantity (say 1 cc.) of the water, 

 and mixing it with melted nutrient gelatine con- 

 tained in a test-tube. After shaking, the contents 

 of the tube are rapidly poured out upon a sterilised 

 glass plate, then allowed to solidify, and finally 

 placed in a damp chamber, kept at about 22 C. 

 After a few days' incubation colonies make their 

 appearance on and in the layer of gelatine. The 

 colonies are counted by means of the eye or lens, 



1 Gazzetta C/iimica Italiana, voL xv. (1885), p. 385. 

 3 Proceedings of Royal Society, 1886. 



* Manuel Pratique d' Analyse Bactiriologique des Eaux (1891), 

 p. 26. 



