320 THE PRESENCE, TYPE, AND POSSIBLE SIONIFICANCE OF LACTOSE-FERMENTING IIACILLI 



III order to see if the coiulitions described by Cluniesha, Aiyar and Mudaliyar* were 

 comparable with those existing in the Sudan, a series of a few experiments, commenced some 

 months ago, was carried out, and they form the subject of a paper wliicli cannot be 

 considered as at all complete owing to tlie fact that they were too few in number and 

 only represented a condition of tilings existing for three months in Khartoum. 



They serve, however, as an introduction to a more prolonged research on the subject of 

 the types of fapcal organisms present in water and soil and the effects of sunlight, etc., on 

 such organisms as have been isolated. 



Khartoum It may be as well to state here the nature of the water-supplies present in Khartoum. 



PP y Qp jjjj j^^.Q y3a,.g ago the town was dependent for the most part on the water taken from 

 the banks of the Blue Nile. Various shallow wells were present in the town, but the native 

 population, as a rule, only used the water from this source for cooking and washing 

 purposes. Now, however, a different state of things exists as most of the shallow wells 

 have been put out of use, and the general water-supply is obtained from deep wells near the 

 Blue Nile. The water obtained from these deep wells is now of great purity both chemically 

 and bacteriologically, as proved by the large number of tests that have been carried out on 

 it at all times of the year. 



The climate of Khartoum is on the whole an extremely dry one. July and August are 

 the chief rainy months. April to June represent the hottest and most dusty months. In 

 September and October the weather is hot and the atmosphere comparatively humid. The 

 Nile as a rule commences to rise at Khartoum in June and reaches its maximum height in 

 September. In November, December, January and February the weather is dry and cool. 



Technique In carrying out the bacteriological analyses of the various water samples the technique 



employed was more or less the one used by Clemesha. About 250 c.c. of the sample were 

 collected in a sterile bottle and the latter was surrounded by ice so as to prevent 

 multiplication of the organisms present. After removal to the laboratory the sample 

 was subjected to the following tests : (1) estimation of the number of colonies present 

 in 1 c.c. of the sample ; (2) enfpritidis sporogenen milk test in 20 c.c. of water ; (3) the 

 pi-esence of lactose fermenters in various quantities of water. Before carrying out these 

 tests the sample was always well shaken. 



1. The total colony count in 1 c.c. 



This was always carried out with agar plates as the heat prevented the use of gelatine. 

 The percentages of the various constituents of the agar was the same throughout all 

 the tests. The acidity was + 10 to phenol-phthalein. One c.c, '5 c.c. and -2 c.c. of the 

 water sample is taken and run into melted agar of a temperature of 41 C. This is then 

 plated out in Petri dishes, incubated at 37" G. for 48 hours, and all colonies visible to the 

 unaided eye are counted. 



2. Sporogenes test 



Twenty c.c. of the sample water are put into sterile milk contained in tubes. The 

 milk is then heated up to 80' C. for 20 minutes, and a layer of hot vaseline is run on to 

 the surface of the milk so as to render the latter anaerobic. The milk tubes are then 

 incubated at 37° C. for 48 hours. 



Evidence of the presence of the spores of Ji. ''titevitidia xpornfjrnen is shown by the 

 clotting of the milk. 



3. The teat for the presence of lactose-fermenting orgaiiiswn and their subsequent isolation 

 Lactose bile-salt-neutral-red-broth is used and, as varying quantities of water are 



inoculated into the tubes containing this medium, the latter is made up in single, double 



• See general account beginning on pagt 333 



