BACTERIOLOGICAL EXAMINATION OF WATER. 79 



lamination of the urine by extraneous organisms. In the 

 male it is usually sufficient to wash thoroughly the glans 

 penis and the meatus with i-iooo corrosive sublimate 

 the tips of the meatus being everted for more thorough 

 cleansing. The urine is then passed into a series of sterile 

 flasks, the first of which is rejected in case contamination 

 has occurred. In the female, after similar precautions as 

 regards external cleansing, the catheter must be used. 

 The latter must be boiled for half an hour, and anointed 

 with olive oil sterilised by half an hour's exposure in a 

 plugged flask to a temperature of 120 C. Here again, 

 it is well to reject the urine first passed. It is often 

 advisable to allow the urine to stand in a cool place for 

 some hours, to then withdraw the lower portion with a 

 sterile pipette, to centrifugalise this, and to use the urine 

 in the lower parts of the centrifuge tubes for microscopic 

 examination or culture. 



The Bacteriological Examination of Water. This may 

 be undertaken with a view to finding either the number of 

 bacteria present or the varieties present. In either case a 

 small quantity (J to i c.c.) is taken in a sterile pipette and 

 added to a tube of gelatine, which is then plated and 

 incubated at the room temperature. In the case of water 

 taken from a house tap, it should be allowed to run for 

 several hours before the sample is taken, as water standing 

 in pipes in a house is under very favourable conditions for 

 multiplication of bacteria taking place, and if this precau- 

 tion be not adopted, an altogether erroneous idea of the 

 number present may be obtained. In the case of the 

 examination of river water, the gelatine plates ought to be 

 prepared on the spot ; at any rate the time elapsing 

 between the sample being taken and the plates being pre- 

 pared must be as short as possible, otherwise the bacteria 

 will multiply, and again an erroneous idea of their number 

 be obtained. When samples have to be taken for transport 

 to the laboratory, these are best collected in four-ounce, 

 wide -mouthed, stoppered bottles, which are to be sterilised 

 by dry heat (the stopper must be sterilised separately from 



