rithmie curves of survivors that differed for 
various cultures. (Fig. 3.). 
Both divert from the straight line, so the 
reaction- or disinfection velocity is not con- 
stant: that of A increases in the progress 
of the process, whereas that of C diminishes '). 
The same types were also observed by H. 
Crick in the case of vegetative organisms. 
Type C was also found by RercneNBAcH 
(ef. tab. XIV—XVI le), who worked with 
very young paratyphus cultures that were 
killed off by heat at 47—49°. When the 
culture was older than 13 hours, the expo- 
nential curve became smoother, once how- 
ever it assumed the shape of type A. 
REICHENBACH attributes the tendency to 
depart from the straight line in very young 
cultures to the relatively large number of 
low-resistant individuals present. It is remark- 
able, that H. Cuick’s experience is just the 
reverse: the value of & diminishes in the 
Logarithms of concen- 
tration of survivors 
4.00 es 
Minutes 
Fig. 3. Coliculture A )0.5%/ Course of the process for the older cultures, 
„ By phenol whereas for the younger ones & is smaller 
at 22° 
and approximately constant. 
As for my own experiments (with Bacillus coli), for the sake of 
uniformity in my material I invariably worked with very young 
cultures and found, as shown in Figs. 2 and 3 departures in either 
way. Added to the contradictory results of the observers mentioned 
above, this seems to suggest that the age of the culture does not 
determine the form of the curve of survivors. 
ec. Yeast cells. 
It being possible that large cells might lead to other results than 
small ones, | also made some experiments with yeast cells. 
There is perhaps some reason to suppose that speaking generally, 
in disinfection experiments, whether with thermal or chemical agents, 
the individuals are destroyed, because the cells, suspended in the 
liquid, are attacked by molecules, whose caloric velocity exceeds 
1) The cultures referred to in Fig, 3 and Fig. 2 are not identical, though from 
the same stock. 
