1334 
Hence we see that the same phagocytes which, after being exposed 
to nitrogen for half an hour, give a considerable increase viz. 
34 5—25.9 
OEE xx 100 = 33.2°/,, show a decreased phagocytosis of 
25.9 
39.4 — 325 ne | 
OL > 100 =17.5°/, after. an jacuon of 4°/, hours, the loss 
of O having become greater in that time. A longer exposure to the 
medium containing little O would probably have lowered the phago- 
cytosis still more. The phagocytes will consume more and more 
their own oxygen. 
IV. Respiratory centre and phagocytosis. Eject of carbonic acid 
and of potassium cyanide. Discussion of the results obtained. 
If we submit the results obtained to a close examination, we 
are struck by the agreement between the effect whieh a withdrawal 
of oxygen has on the respiratory centre on the one hand, and on 
the phagocytes on the other. 
After the many researches on the respiratory centre we may take 
it for granted that, besides by the action of carbonie acid, the respi- 
ratory centre is also stimulated by a withdrawal of oxygen. 
If in an animal the O-pereentage of the blood is increased by 
frequent deep respiration, then this respiration may be stopped for 
some time without the animal showing any need of it (apnoea). 
Under these circumstances the stimulus passing from the respiratory 
centre on to the nerve centres of the respiratory muscles is evidently 
too weak to act upon it successfully. Likewise with the phagocytes 
we observe that a considerable increase of the O-supply leads to a 
decreased activity, a decreased phagocytosis. Af the O-percentage 
decreases, the phagocytes are stimulated into a higher activity, the 
phagocytosis increases, while it decreases more anil more, subsequently, 
as more O is lost, in accordance with the fact that all cells of the 
animal organism need oxygen, if they are to continue their functions. 
The respiratory centre too increases its activity when O is very 
scarce (dyspnoea), and is paralyzed when O continues to be withdrawn. 
Hitherto we have made no quantitative comparisons between the O-percentage 
of the fluid in which the phagocytes are paralyzed, and that in which the nervous 
centre refuses to act. These comparisons, however, can only relate. to the medium, 
hardly to the cells themselves. In view of these considerations and also owing to 
the fact that a quantitative determination of phagocytosis is very liresome, no 
experiments have been made in this direction. It may be expected that the respira- 
tory centre will be more sensitive to a withdrawal of oxygen than the phagocytes. 
The higher nervous centres are certainly still more sensitive than the respiratory centre. 
