630 
beirig an exponential curve, will become a straight line inclining 
to the abscissae, if we take the logarithms of the numbers of 
survivors instead of the numbers themselves. 
By expressing the results of the experiments logarithmically, we 
can see at a glance whether, and how far, they are in accordance 
with the formula, or whether they depart from it; the absolute 
values being immaterial in this case, I used for my calcuiations 
Briae’s logarithms in place of natural logarithms. (ef. H. Crrck). 
In order to account for their results MapseN and Nyman regard 
anthrax spores as an aggregation of individuals of differing resistance. 
If however this dissimilarity were decisive, a totally different type 
of “curve of survivors” could be expected, as I demonstrated in the 
Biochem. Zeitschrift (Bnd, 11. 1908). Conformably to the frequency- 
curve of QuéreLeT-GALTon au accumulation of deaths could then be 
expected at an average moment of the process, the rest of the spores 
with a lower or higher resistance, dying before or after it in gradually 
lessening numbers. Consequently the curve of survivors would neces- 
sarily assume the ~_-form or, when represented logarithmically, the 
N-form and not the shape of \. (see also fig. 6, page 637). 
Experiments with bacillus coli, published by me in a previous 
paper really brought forward a curve very much like it, which 
however differed from the one expected in not being symmetrical, 
as the first half of the germs were killed in much shorter time than 
the second. 
In the case of anthrax spores I obtained since that time results 
in fair accordance with Mapsen and NyMman’s experience, just as 
H. Crick '), Retcuenspacn *) and others did. 
a. Experiments with anthrax spores. 
Fig. 1 shows the results of three experiments on disinfection 
at 80°, 84° and 90°, expressed logarithmically. Their accordance 
with the formula may be called very satisfactory. The deviations 
from the straight lines, inclining to the abscissae, are indeed 
slight. An exception is noticed only at the beginning of the experi- 
ment at 80°, where there is hardly a fall in the number of bacteria 
during the first few minutes. The same had occurred very regularly 
in my previous experiments with Bacillus coli, This period of lag 
I then took to be an incubation. I learned since, that an analogous 
1) The Journal of Hygiene, Vol. VIII 1908, Vol. X, 1910. 
®) Z. f. Hyg. u. Inf. Kr. Bnd, 60, 1911. 
