Microscopical examination showed that in the NaCl-solution of 
1,1°/,, 1,2°/,, and 4,8°/, all the lencoeytes had regained their: round, 
shape, while in the isosmotic NaCl-propionate solution nearly all the 
cells still had pseudopodia. 
Even in the NaCl-solution 0,9°/, relatively few leucocytes with 
pseudopodia were found, and yet the phagocytosis had reached about 
the same stage as in the latter fluid, which contained much propionate 
(12,7°/, and 15°/, respectively). 
It follows from this that propionate has the property of influencing 
the amoeboid motion of the leucocytes in a favourable sense; one 
might be inclined to say that they are made more resistant. 
For what was observed to take place? 
In the NaCl-solution 0,9°/, the leucocytes drew back their protru- 
sions owing to the lower temperature, but in the propionate-sol. 
with the same degree of phagocytosis they remained, notwithstanding 
this low temperature. 
Similar results were arrived at in the experiments of Table II: 
in NaCl 0,9°/, no pseudopodia, in NaCl combined with propionate 
1:100, 1: 250 and 1:1000 many pseudopodia, in propionate 1 : 5000 
fewer, and in 1: 25000 and 1000.000 none. 
Now it would be incorrect to look upon the promotion of phago- 
cytosis and the capacity of resistance of the pseudopodia as being 
identical. 
First there are a number of leucocytes which protrude pseudo- 
podia, but which show no phagocytosis, and secondly it appeared 
from another series of experiments with propionate and CaCl, where 
both substances equally promoted phagoeytosis, that after being cooled 
down and fixed, the microscopic pictures were entirely different. In 
the CaCl,-solution namely the lower temperature had caused the 
pseudopodia to disappear almost entirely, in the propionate-solution 
on the other hand, this was not the case. 
But since the formation of pseudopodia is one of the conditions 
for phagocytosis, it may be concluded from the observation with 
propionate that propionate by influencing the formation of psendo- 
podia in a favourable sense has contributed to the promotion of 
phagocytosis. 
That the effect of propionate is due to a surface-action and not 
to a direct action on the contents of the cells appears from volume- 
trical determinations, 
The volumes of two equal amounts of blood corpuscles, exposed to 
the action of isosmotie solutions, are equal, as we know, but only 
on condition that the substances do not penetrate into the blood corpus- 
