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faction are both checked by the appearance of the acid in the 
nutrient medium. 
3. The virtual gelatine-liquefaction-halo, which one can construct 
by means of EiJKMAN’s gelatine-stripe method *), is, it is true, not 
congruent with the haemodigestion-halo in the blood-agar plate; 
but on the oxyhaemoglobin plate the halos come very nearly together. 
4. The strains that are strongly haemodigestive consume casein 
also intensely; the identity of the casein-digestive and the gelatine- 
liquefying ferment has been made. very plausible by Etykman, by 
means of the gelatine-stripe method. 
SNAPPER’s discovery that the digestion of blood has a much quicker 
process in blood-bile-agar than in blood-agar, incited me to put my 
hypothesis, stated before, to the test and to enlarge my investigations 
on the decomposition of oxyhaemoglobin by other bacteria as well. 
I want to refer to the fact that the origin of the greenish and 
clear halo round the colonies of a haemodigestive choleravibrio on 
the blood-agar plate is actually based on transformation of the 
oxyhaemoglobin (SNAPPER entered into the details of this to confirm 
my previous spectroscopic research): first haematine-like bodies ori- 
ginate, which are decomposed in the course of the experiment. 
This. is also obvious in the decrease of the greenish colour near 
the stripe-culture, while the pyridin-chromogen reaction takes place 
slower at that point than at a greater distance from the culture. 
On oxyhaemoglobin plates on which, as I pointed out before, the 
process of the digestion of the oxyhaemoglobin is to be seen clearly 
with the naked eye by the zones of different colour, it is possible 
too to indicate the further decomposition of haematin by means of 
pyridin and sulphurammonium. On the blood-bile-agar plate the 
cholera vibrio is sustained in the digestion of the oxyhaemoglobin. 
By the action of the bile on the blood, the haemoglobin has not 
only come out (as is the case in the oxyhaemoglobin plate), but has 
been transformed into haematin-like substances besides. The process 
of decomposition is progressing already considerably when the cholera 
vibrio begins to influence it, which is revealed in the quick forma- 
tion of a broad clearly transparent and colourless halo round the 
1) The gelatine stripe method is executed by bringing, by means of a platinum- 
loop, stripes of liquefied gelatine close to the culture on the agar plate. The 
gelatine becomes solid at an ordinary temperature; so it is possible to trace how 
far the gelatine stripe (after some time at 22° C. e.g.) disappears from the 
culture by the action of a ferment. 
The figures in this text show how one may construct the gelatine liquefying 
halo in this way. (In Fig. 1 e.g. the white dotted line). 
