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blood-bile plate and do not cause the gelatine to liquefy. Both these 
results are in favour of the identity of the actions in question. 
I want to make one more remark; as l pointed out before, some- 
times one sees in an organism, of which the casein balo and the 
gelatine halo cover each other entirely on a nutrient medium, that 
their congruence has disappeared on another nutrient medium. 
; When glycerine has been added to the casein plate, on which 
the cholera vibrio is inoculated, the virtual halo of liquefaction 
will remain at some distance within the halo of casein-digestion. 
So I observed also that the halo of gelatine-liquefaction in a 
strongly haemodigestive coccus, isolated from the air, is a little larger 
than the halo of the haemodigestion (on the blood-bile plate). The 
above-mentioned experimental experience teaches us that this does 
not contain an argument against the identity of the haemodigestive 
and collolytic bacterial action. 
I conclude by remarking that these experiments teach us that 
the blood-bile plate as well as the casein plate may serve for the 
substitution of the broth-gelatine in determining bacteria. This is 
an advantage while working in tropical littorals, where the use of 
the nutrient media is subject to difficulties owing to the high tem- 
perature of the air. 
Amsterdam, Institute of tropical hygiene, department 
Mareb 1920. of the Colonial Institute. 
