VM 
SEDGWICK AND WINSLOW. — BACILLUS OP TYPHOTD ri:Vi,Il. 
Stock, Kace B, the reduction was over 99 per cent. The reduction now jji-.u. ..],, 
however, with increasing slowness ; the two or tliree germs per tlionsniid \vl,i,.l, UiyQ 
survived thus far appear to possess special powers of resistance. Even alYur ] 2 v?^U 
few of the individual tubes were rendered sterile. These results appeared <n reruark- 
able that special experiments were conducted to test their accuracy, as it wm felt 
that perhaps the few germs developing from the thawed ice might have Lctn inlro- 
duced from the air, as was obviously the case in some instances. Fifty tub*- of 
Races B and C were therefore frozen for periods of a week and a month; plale^ 
were planted from tliem, with special precautions, and incubated at 37.6 ; nnr? 
the developing colonies were examined individually. The results, as the njiju ixbd 
tables show (see p. 492), confirm those of the general investigation. Of the 20 tuhos 
inoculated with Race B and frozen for a month, 10 were sterile; 9 gave one hfcrilo 
plate, and one with one or two colonies of what j^roved to be extraneous germs; tui.e 
IV. alone gave, on one plate, 7 germs per cubic centimeter, wliicJi examination in 
the hanging drop, and growth on gelatine, and potato, in milk and glucoso poIu- 
tion, showed to be the original typhoid culture. So of the 30 tubes of Race C 
frozen for a week, 17 were sterile ; 9 showed contamination, one or two gerrn« 
per plate; the other four showed 15, 4, 1, and 267 typhoid bacilli per cubic c<n- 
timeter. These experiments confirm the results of those observers who froze 
typhoid cultures containing millions of germs without effecting sterilization. 
3. Prudden's statement that the number of bacteria killed by freezing varies 
with the species may be extended. It is evident that within the species B. typhi 
abdominalis there are races, each having a power of resistance of its own, depen- 
dent upon its history within and 
for the shorter periods of freezing 
) body. A comparison ol 
•ly that Race C succumbed 
I 
greater readiness to the Influence of cold than did Race B ; while Races A 
D occupied an intermed 
These differences appear constant through 
various sets, so that in each race the progressively increased reduction with more 
prolonged freezincr follows a narallel course. The facts cannot, we think, be at- 
P 
tributed to differences in the immediate environment of the germs; such differ- 
ences do produce their effect, cultivation for a time on agar, for example, causlnir 
a decrease in resistance. The last sort of change is, however, temporary and may 
be quickly reversed by cultivation in bouillon; while the race dilTerunccs were 
permanent during the period of experimentation. Correlated with them were cer- 
tain minor characters; for instance, the weakest race, Race C, grew more slowly 
than either of the others, and took perceptibly longer to produce a ^lefinitc 
clouding in a liquid medium. 
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