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8CIENGB. 



[Vol. IX., No. 21» 



which he reviews the evidence presented by those 

 who hare maintained these several theories, and 

 gives the results of some twenty experiments of 

 his own made on fifty frogs. He suspended the 

 legs of the frogs while living in an artificial gas- 

 tric juice (that is, pepsin and hydrochloric acid), 

 and found that the muscular tissue was digested, 

 as was shown by the presence of peptone, the 

 frog remaining alive throughout the experiment. 

 When acid alone was used without the pepsin, 

 the muscle was softened and dissolved, but not 

 peptonized, and therefore not digested. It thus 

 appears that living tissues may be digested, and 

 that the problem is as far from solution as ever. 

 Dr. Warren comes to the same conclusion, but 

 promises to investigate the subject more fully in 

 the future. 



In a recent number of Science we referred to 

 the experiments of Dr. T. M. Prudden on bacteria 

 in water, with special reference to the ice-sapply 

 of New York City. These experiments were not 

 confined to the water, but included also the ice 

 itself. These observations show that ice formed 

 in the Hudson River near Albany contains vastly 

 greater numbers of bacteria than that found at 

 some distance below, but that, notwithstanding 

 the fact that the water of the river is freed to a 

 certain degree from bacteria after running some 

 distance, the average number of bacteria left in 

 the ice is considerably above that which can be 

 regarded as wholly safe. Samples of ice from the 

 various lakes and ponds from which the supply 

 of New York is taken have also been analyzed. 

 The general conclusions to which Dr. Prudden 

 has arrived may be thus summarized : 1°. A 

 biological analysis of water and ice will detect 

 the presence of bacteria, some species of which 

 can give rise to serious disease, but a great deal of 

 careful study of other conditions is still necessary 

 in order to determine whether the water or ice is 

 suitable for use or not ; 2°. In freezing, water 

 purifies itself only partially, the gross particles 

 and some of the materials in solution being re- 

 moved, but the bacteria remain to a considerable 

 extent unaffected ; 3°. Different species of bacteria 

 possess differing degrees of vulnerability to the 

 action of low temperatures ; 4*. The bacillus of 

 typhoid-fever and the common bacteria of sup- 

 puration are capable of resisting a prolonged ex- 

 posure to a low temperature with the destruction 

 of a part only of the individuals thus exposed ; 

 5°. Experimental data justify the belief that in 



natural waters there may be a purification of 

 about ninety per cent ; 6°. In filtration of water 

 the various species of bacteria, dangerous and 

 harmless, are eKminated with about equal efficien- 

 cy, while in freezing the dangerous disease-pro- 

 ducing species may be retained if they resist low 

 temperatures, while more or less of the harmless 

 forms may be destroyed ; 7°. The ice supplied to 

 New York comes from a series of naturally excel- 

 lent lakes and ponds, and from a great tidal river 

 largely contaminated in its upper regions, and by 

 far the larger proportion of the ice comes from 

 the latter source ; 8". A very much greater num- 

 ber of bacteria are found in snow-ice and in the 

 very bubbly streaks than in the transparent ice, 

 particularly in the snow-ice on the top of the 

 cakes ; 9°. The average number of bacteria in ice 

 from all sources taken together is far beyond the 

 general standard which even a moderate degree 

 of purity would allow ; 10°. The transparent ice 

 from some of the lake and pond sources presents 

 in general a most admirable degree of freedom 

 from bacteria. 



In interpreting the results which he has reached, 

 Dr. Prudden states that typhoid- fever, and dis- 

 eases associated with acute suppuration and the 

 so-called blood-poisoning from wounds, or pyaemia, 

 are almost constantly present in large towns like 

 Troy and Albany, and frequently so in villages 

 like many of those which lie along the upper 

 Hudson ; and that his experiments have shown 

 that the bacteria causing these two forms of dis- 

 ease are markedly resistant to the temperature at 

 which ice forms. He estimates that in Albany 

 alone, there are, on an average, fifty cases of 

 typhoid-fever whose excreta pass into the Hudson 

 River each year during the ice-forming season. 

 He also finds that in that city there is no syste- 

 matic disinfection of the typhoid discharges, 

 which therefore enter the sewers, and subsequently 

 the river, with their myriads of bacteria in a liv- 

 ing condition. Dr. Prudden recommends that the 

 state board of health, or other authority, shall 

 have full control of the ice-harvesting fields, and 

 determine which, if any, of the sources of ice-sup- 

 ply are so situated as to imperil the health of the 

 consumers of the ice. In addition to this, a com- 

 pulsory system of disinfection of excreta in infec- 

 tious diseases should be instituted. He also thinks 

 that artificial ice might, perhaps, be substituted for 

 the natural ice. In concluding his very valuable 

 paper, the writer expresses his sincere hops that his 



