ICE 275 



Dr Prudden, of New York, performed a series of experiments in 

 1887 to show the relative behaviour of bacteria in ice. Taking half 

 a dozen species, he inoculated sterilised water and reduced it to a 

 very low temperature for a hundred and three days, with the 

 following results : B. prodigiosus diminished from 6300 per c.c. to 

 3000 within the first four days, to 22 in thirty-seven days, and 

 vanished altogether in fifty-one days; a liquefying water bacillus 

 numbering 800,000 per c.c. at the commencement, had disappeared 

 in four days ; Staphylococcus pyogenes aureus and B. fluorescens showed 

 large numbers present at the end of sixty-six and seventy-seven days 

 respectively ; B. typhosus, which was present 1,000,000 per c.c. after 

 eleven days, fell to 72,000 after seventy-seven days, and 7000 at the 

 end of one hundred and three days. Anthrax bacilli are susceptible to 

 freezing, but their spores are practically unaffected (Frankland). From 

 these facts it will be seen that bacteria live, but do not multiply, in ice. 



Hutchings and Wheeler recently examined some ice suspected of 

 conveying typhoid fever at the St Lawrence State Hospital on the 

 river St Lawrence. The fragments were melted in a clean vessel at 

 room temperature, after which a considerable black sediment deposited 

 itself in the vessel. Cultures and plates were made in the usual 

 way, and B. coli and B. typliosus were both isolated.* The last- 

 named had the following characters : On nutrient agar it grew 

 readily, in broth growth without pellicle, in lactose media no fermenta- 

 tion occurred, on potato the " invisible " growth, litmus milk became 

 alkaline without coagulation, and the bacillus was morphologically 

 identical with B. typhosus. With the serum of typhoid patients 

 characteristic agglutination occurred. Blumer found the number 

 of bacteria in some of the same ice was 30,400 per c.c. (agar) and 

 50,400 per c.c. (gelatine). Many colon bacilli were present. 



Sedgwick and Winslow have also carefully studied the influence 

 of natural and normal conditions of cold upon the typhoid bacillus 

 in particular. The experiments were carried out with special refer- 

 ence to the danger of conveyance of the disease in question by 

 polluted ice, and with reference to the seasonal distribution of the 

 disease. The matter was undoubtedly one that called for investiga- 

 tion, and notably so in America where ice and iced drinks are in 

 such universal demand. 



The apparent purity of ice is deceptive. It is true that water in 

 freezing undergoes a certain amount of purification. It loses, on 

 conversion into ice, saline constituents, contained air, and a certain 

 proportion of organic suspended matter. At the same time, it is not 

 entirely freed from microbes. The figures quoted by Sedgwick and 

 Winslow show that snow-ice may contain an average of more than 

 600 bacteria per cubic centimetre. 



* American Jour, of Medical Sciences, Oct. 1903, p. 683. 



