656 
a certain limit. A slow process would induce us to think, that these 
active molecules with a caloric velocity far beyond the average, 
are only small in number, all the rest being comparatively indiffe- 
rent. The micro-organisms are then as it were exposed to a contin- 
nous shower of bullets (the active molecules) and if this shower be 
not too dense they will be destroyed in succession and in obedience 
to the mass-law. Thus the analogy with the unimolecular reaction 
would be rendered intelligible. 
Now, just as in a shower of bullets, the number of “hits” in our 
case depends on the size of the targets, the larger the individuals 
are, the more regularly the hits will be distributed among them. 
We were therefore justified in supposing that, whereas the smaller 
organisms behave in analogy to the unimolecular reaction, the 
individual differences of resistance existing among the larger ones 
become more prominent and express themselves in the form of the 
curve of survivors. 
I do not mean to attach great importance to this illustration, nor to 
offer its validity as a point to be discussed. I only wanted to set 
forth why I extended my experiments to larger organisms also. 
Numbers of ; 
germs EE a Pi Numbers of germs —= ~~~ ~~ log. 
1000 1000 
0” 10:5 208300 Ape (50. you 
Minutes Minutes 
Fig. 4, Rose yeast killed at 47°. Fig. 5. Rose yeast with 0.60/, Phenol at 25°, 
