i 
SEDGWICK AND WINSLOW. — liACII.I.r? OF TYHIOTD KKVJJt 
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H. EXPERIMENTS ON THE EFFECT OF AJ.TKii.NATK FI:KI:ztN0 ANI> ilUUIN.; 
uroN THE BACILLI OF TYriioiD ri:vi:i!. 
Dr. Prudden, as we have seen, considered intermittent more fatul than iniinl. t. 
upted freezing, and, indeed, succeeded in one case in entirely jstcrillzing a <nl»«- 
inoculated with B. typhi by this method. Our four Forics of cxpcriinont,« on \\{\n 
subject were conducted by freezing tubes in ih^ freezer as dc cribcd in the prr-vloiw 
section. The tubes of Series I, Race A, were frozen daily for five days and nllo\v<'d 
to thaw each time after about eighteen hourf, samples being planted after cnrh 
thawing. Those of Series I, Race B, were frozen three times, on alternate days, 
remaining frozen for twenty-four hours each time and kept below 2' for the rest nf 
the tune. The two series in Race D were treated like the tubes frozen for three hnnr« 
and six hours in the last section, except that instead of remaining frozen thoy \\ tic 
thawed and refrozen once and twice respectively during that time. 
The results of these experiments with the results of simple freezing directly com 
parable are as follows : 
Frozen once in one day . . . 
Frozen twice in two days . . . 
Frozen three times in three day 
Frozen four times in four days 
Race A. 
y(;.i 
<iS<J 
if.+.r* 
. . 00.8 
Race B. 
Kept frozen for three days (see previous section, Race B, Series III) 0"! 
Frozen twice in four days * .' ' ' ., «* 
Kept frozen for seven days (see previous section, Uace V», S.-nefl llj IKj-*? 
Frozen three times in six days ' ' 
Rape D. 
Kept frozen for three hours (see previous section, Ence D, Series I) <4. 
Kcfrozen once in three hours 
1»7.0 
Kept frozen for six hours (see previous section, Race I), Series 11) • ^^ 
Refrozen twice iu six hours 
Conclusion. ThawinL^ and refreezin- are somewhat more fatal than simple fror-7- 
Four successive freezings and fhawings do 
O "-"^^ ^v^-'-^ -, 
V - 
J"g in its effect on the typhoid bacilli 
not, however, suffice to kill off the nios 
