470 



NA TURE 



[September 13, 1894 



themselves. There are, however, two subjects on which 

 it is necessary to make some comment. The first refers 

 to a passage on p. 119; they say : "In the year 1SS5 

 Koch's gelatine process of water examination was first 

 introduced into this country by one of us." 



I am quite sure that Prof. P. Frankland hereby quite 

 unintentionally omitted to state the fact that Dr. -Angus 

 Smith {The Sanitary Record, 1SS3) was the first to apply 

 the gelatine test for showing the relative number and 

 the different characters of the colonies of the microbes 

 present in water. 



The second point refers to the factors which determine 

 the efficient character of sand filters. From p. 119 to 

 p. 142 we have a detailed account, with numerous tables, 

 of the results of the bacteriological examination of 

 London waters " by one of us,' yet no mention is made 

 and no indication is given of one of the most important 

 factors [arteris paribus) in efficient sand filtration, viz. 

 the formation in the superficial layers of the filter bed 

 of a slime (Schlamm) ; it is precisely after the formation 

 of this " slime " that the filter becomes efficient, it is 

 inefficient before the "slime "is formed. The authors 

 have had abundant indications as to the importance of 

 this "slime"; they quote on p. 158 researches byPiefke, 

 who demonstrated already in 1.SS7 that (p. 159) "it is 

 the slime deposit on the sand which constitutes the real 

 filtering material in the water-works' filter.' Further 

 indication of the importance of this "slime' was given 

 to the authors by Prof. Lankester's extremely valuable 

 evidence before the Royal Commission on Metropolitan 

 Water Supply, November 1S92, and lastly by Koch's 

 paper on water filtration in the Zeitscln-.f. Hvi^icnc und 

 In/ektions, vol. xiv. Koch clearly shows that the sooner 

 this slime is formed— water which initially contains a 

 greater amount of impurity would form it sooner tlian 

 water initially pure — the sooner the filtration becomes 

 efficient ; further, that on renewal (by scraping) of the 

 surface of the filter this protective slime is removed, and 

 therefore the filter for the time becomes inefticient ; 

 then the influence of frost on this slimy layer, and a 

 variety of other important points connected with this 

 slime. All these and others are of the utmost import- 

 ance as regards the real understanding of the working 

 of sand filters; e.g. the exact nature of the slime, the 

 conditions affecting its formation, the differences of its 

 formation in the filter-beds of the various London Water 

 Companies, and at various periods, &c. All these points 

 require elucidation, and one must regret that the authors 

 have missed a valuable opportunity to treat of these in 

 the book ; since the researches "by one of us' made of 

 the London waters in 18S6, which are quoted in full in 

 the work, no real progress appears to have been made. 

 One thing, however, is brought out by the observations 

 not only of Fraenkel and of Piefke, but of all that have 

 worked on the question of purification of drinking-water 

 by filtration, and that is (p. 157) that "even under the 

 most favourable conditions of working the sand filters 

 do not form a complete obstacle to the passage of 

 micro-organisms." 



Chapter vii., on the detection of pathogenic bacteria 



in water, gives an extensive bibliography and the most 



reliable methods for the detection of bacteria, the typhoid 



bacilli, and Koch's comma bacillus receiving a not undc- 



NO. I29S, vol.. 50] 



servedly large share of attention. With regard to the 

 differentiation of bacillus coli and typhoid bacillus by the 

 presence or absence of gas-bubbles in gelatine cultures, 

 the authors state (p. 269) : " This distinction has been 

 shown by one of us to be available in an extremely 

 simple form for the differentiation of the two organisms, 

 viz. the bacillus coli forming gas-bubbles in gelatine 

 shake cultures already after twenty-four hours' incubation 

 at ordinary temperature, while the bacillus of typhoid 

 does not do so. I am able to confirm this, and to state 

 that this characteristic formation of gas-bubbles by 

 bacillus coli in gelatine shake cultures has been known 

 and practised in my laboratory for more than two years, 

 and is described by me in the Reports of the Medical 

 Ofticer for the Local Government Board, 1893-1893: 

 also in the Journal of Pathology and Bacteriology 

 November 1893 ; and in the Centralblatt fiir Backt. uiul 

 Parasit. vol. xv. Nos. 8 and 9. 



There is one further subject to be mentioned, viz. on 

 p. 272 and p. 273. The authors in using Parietti's 

 method, in order to detect the typhoid bacillus in water, 

 recommend adding to the cultivating mediuin " i to 10 

 drops of the water under investigation " ; if, as is almost 

 invariably the case, the typhoid bacillus is present in the 

 water in a highly diluted state, i.e. few examples in a large 

 bulk of water, how the authors can under these con- 

 ditions hope to recover the typhoid bacillus by using 

 I to 10 drops of the water, is difiicult to see. True, later 

 on, on p. 285, an important addition //; small print is 

 made in the shape of a note at the end of chapter vii., to 

 the eftect that in " examining water for the typhoid 

 bacillus it is advisable to pass a considerable volume, 

 250 c.c. or upwards " (this sounds rather different from 

 I to 10 drops) "through a sterile porcelain or infusorial 

 earth filter, and then to transfer this deposit on the sur- 

 face of the cylinder by means of a sterile brush into a 

 small quantity of sterile water' ; this is then used for 

 cultivation. This is the identical method which was 

 used by me with success in the summer of 1S93 in de- 

 tecting the typhoid bacillus in the Worthing water, and 

 soon after in the water from a polluted well in Rothei- 

 ham.' 



For the means by which Koch's cholera vibrio can be 

 differentiated from other vibrios that have been hitherto 

 found in water, the authors (on p. 279) mention Koch's 

 conclusion that the absence of indol reaction, as well as 

 the absence of any pathogenic effects on guinea-pigs, 

 sufficiently distinguish the non-cholera vibrio from Kocl^^ 

 comma bacillus. This conclusion is definitely contra 

 dieted by a number of more recent observations made by 

 independent workers, amongst them notably R. PfeitVer 

 {Archil'. /. Hyg. und Infekl. vol. xvii.). 



Chapter viii. treats of the vitality of particular patho- 

 genic bacteria in diflerent waters ; a large amount of 

 bibliography with tabulated results by the various author 

 are given /// cxtenso. Turning to the vitality of tli 

 typhoid bacillus, we find one observer (p. 2901, liraeri' 

 gives the vitality of this bacillus in distilled water i^^ 



I A .similar rcm.irk m»y lie m.idc lo a p.isugc on p. sSj. The aulliors m 

 de^cnhinf! tlic <lelcction of .inthrax sporcit in water, stale : — "A meltiod li.Tt 

 been ilrviseil by one of u» (1893) suitable for the detection of anllir.iv sporn 

 when present alonK witbotJier micro-organilins in water." Tflis cunsi^tftlit 

 killins by heat the non-.pore-bearinn forms while the sporc^., beinc more 

 re«i%lini:, nmvive. Thi« method " one of u»" niii;ht have found described 111 

 Klein's " Micro organism and IJi^ea«e," 3rd edition, 1886, p. 106. 



