49 
1889-90.] Dr G. E. C. Wood on Enzyme Action. 
the state of development of the enzyme function, a factor which, 
must be constantly borne in mind in all such investigations. In 
each organism the range of variability, as regards its enzyme action 
and varying susceptibility, is a specific quantity depending on the 
nature of the protoplasm, and can only be determined by direct 
experiment. 
The greater sensitiveness of organisms when grown with exclusion 
of the air may be of more general interest, as perhaps throwing light 
on a question which has long remained obscure — the manner in 
which certain diseases are propagated. In cholera, typhoid, and 
yellow fever, the intestinal symptoms predominate, and it is through 
the evacuations that the poison is disseminated. Yet although the 
organisms are present in large numbers, in the case at least of the 
first two diseases, direct infection from the fresh stools is by almost 
general consent considered the exception rather than the rule. 
Pettenkofer has emphasised and attempted to explain this view, 
especially in the case of cholera, by assuming that the organisms do 
not leave the intestine in a condition capable of infecting others, 
but that they must first undergo a process of “ ripening ” in the 
soil. It has been suggested by others that the organisms must first 
grow outside the body to form spores, and that these may be the 
only means of infection. This is, however, completely negatived 
by direct bacteriological investigation. Now, the mode of existence 
of organisms in the intestine must be from the first practically an 
anaerobiotic one. The small quantities of oxygen which are 
swallowed with the food are rapidly absorbed by the walls of the 
stomach, or converted into carbonic acid by the organisms always 
found there, so that, in the upper straits of the small intestine, at 
most, only traces of oxygen can be present. Experiments carried 
out by Hueppe and myself, have shown that cholera can under 
precisely these conditions produce its poison in great quantity. 
But if the organism lives anaerobiotically in the intestine, it will 
leave it in a peculiarly sensitive condition, especially as regards 
acids. This greater susceptibility to acids would raise a barrier to 
its passage through the stomach, through which infection must 
occur. But, if allowed to grow in contact with the air, as on soiled 
linen, they would acquire their normal power of resistance, and 
with it that fearful infectiveness which has been, under such cir- 
VOL. xvii. 26/2/90 D 
