TRANSACTIONS OF SECTION D. 731 



4. On the Conditions affecting Bacterial Life in River Water. 

 By E. Frankland, JD.C.L., F.E.S. 



lu a series of monthly observations, the author found that the microbes in the 

 water of the Thames and Lea are, as a rule, much more numerous in winter than 

 in summer. Tliere are three conditions, to any one of which this difterence might 

 be attributed, namely, temperature, sunshine, and rainfall. By a series of graphic 

 representations these thi'ee conditions are disentangled from each other by placing 

 the results of the microbe determinations in juxtaposition with (1) the temperature 

 of the water at the time the samples were taken ; (2) the number of hours of sun- 

 shine on the day and up to the hour when the sample was drawn, and on the two 

 preceding days ; and (3) the flow of the Thames over Teddington Weir on the 

 same day expressed in millions of gallons per twenty-four hours. Altbough the 

 graphic representations were confined to the Thames, the conditions affecting bac- 

 terial life in this river are doubtless equally potent in other rivers and streams. 



These graphic representations afford definite evidence as to which of the thi'ee 

 conditions just named has the predominant influence upon bacterial life in river 

 water. They show that whilst coincidences between a high number of microbes 

 and a low temperature and absence of sunshine are not wanting, some other condi- 

 tion entirely masks tl;e effect, if any, of temperature and sunshine. This condition 

 is the amount of rainfall higher up the river, or, in other words, the volume of 

 water flowing along the river-bed. 



The interesting observations of Dr. Marshall Ward leave no doubt that sun- 

 light is a powerful germicide ; but it is obvious that its potency in this respect 

 must be greatly diminished, if not entirely annulled, when the solar rays have 

 passed through a stratum of water of even comparatively small thickness before 

 tliey reach the living organisms ; and the author shows, by a series of experiments 

 upon the efl'ect of sunlight upon the river water at various depths from the surface, 

 that the germicidal effect of sunlight on Thames microbes is nil at depths of one 

 foot and upwards from the surface of the water, even when the river is in a com- 

 paratively clear condition. It cannot, therefore, excite surprise that the efl'ect of 

 sunshine upon bacterial life in the great mass of Thames water should be nearly, 

 if not quite, imperceptible. 



The author also calls attention to the powerful effect of storage reservoirs in 

 the diminution of the number of microbes in river water, and to the very important 

 bearing which this fact has upon the storage of flood water in the Thames Valley, 

 for it leaves no doubt that storage for a month or two of the flood waters would 

 efl'ect such a bacterial improvement as would render the water of good quality 

 for domestic use. By the construction of such storage works, the capacity of 

 the Thames basin for the supply of good potable water to London would be enor- 

 mously increased. 



5. On the Exploration of the Islands of the Pacific. 

 By Prof. A. C. Haddon. 



6. On the Coccidce of Ceylon. By E. E. Green. 



Since the publication of bis papers on Lecanium viride and C/nonaspis biclacis, 

 the author has devoted three years to continuous work upon the (Joccidse of Ceylon. 

 He has recorded 150 species, of which fully two-thirds were new, and found it 

 necessary to create two or three new genera for the rece])tion of strikingly aberrant 

 forms. He referred to newly discovered organs in the encapsulated male, and 

 remarked that he had in preparation a monograph, to be illustrated by 120 or more 

 plates, giving figures of adults and larv;e drawn i'rom life. On his return to 

 Ceylon he contemplates continuing the investigation in both its scieutiBc and 

 economic aspects. 



