122 
1 
tention. When lying quietly at rest, there 
was no apparent change in the respiration. 
No graphic records or measurements of the 
minute volume were taken. But when the 
dog was urged to rise and walk about, it at 
once began to pant violently. On lying down 
again, the panting ceased. Other dogs with 
normal cerebral circulation did not pant ex- 
cept after much greater exertion. 
Hill states that none of his dogs died after 
ligation of the four cerebral arteries, but he 
does not mention the age of his dogs. I have 
found that vigorous, full-grown dogs survive 
the ligation indefinitely, but half-grown pups 
and old dogs usually succumb within twenty- 
four hours. I have seen half-grown pups lie 
unconscious for several hours, sometimes pant- 
ing violently, and sometimes making ineffec- 
tual movements of locomotion with the fore 
limbs. Attempts to rouse them from this state 
were unsuccessful, and they were usually 
found dead the next morning. 
Hill remarks that there must be a certain 
blood pressure resulting in the flow of a cer- 
tain amount of blood through the medulla 
oblongata in order to provoke respiration. 
My experience tends to confirm Hill’s con- 
clusion. It is a striking thing to see an ani- 
mal with failing respiration at a low blood 
pressure improve rapidly when the pressure is 
artificially increased. 
In the dogs with restricted cerebral circu- 
lation, there was no apparent deficiency in the 
rest of the systemic circulation in those which 
recovered. Nor is there any reason to suppose 
that there was any change in the blood which 
would decrease its power of carrying either 
oxygen or carbon dioxide. It does not seem 
improbable that, in the dog with the marked 
respiratory disturbance, one would have found 
a somewhat greater concentration of oxygen 
and a somewhat lower concentration of carbon 
dioxide in the blood than in dogs with normal 
circulation. The condition in the medullary 
center itself, in which carbon dioxide might 
tend to accumulate in somewhat greater con- 
centration than usual, would seem sufficient 
to account for the dyspnea on moving about. 
A lower concentration of carbon dioxide in the 
SCIENCE 
[N. 8. Vou. XLVIIT. No. 1231 
blood would be the natural result of the forced 
respiration. In cases of shock resulting from 
abdominal wounds on the battle field, in which 
there was no deficiency of the systemic cir- 
culation prior to the wound, it does not seem 
necessary to assume the production of any 
large quantities of acid in the body to account 
for the lower concentration of carbon dioxide 
in the blood of such patients. It seems suffi- 
cient to suppose that, as the systemic blood 
pressure falls progressively lower, there would 
be a deficient blood supply to the respiratory 
mechanism in the medulla oblongata. The 
natural result would be an increase in the vol- 
ume of respiration, and a decrease in the con- 
centration of carbon dioxide in the blood. 
This would not in itself be a sufficient reason 
for postulating acidosis as a causative factor 
in the early stages of shock. Whatever acid 
might accumulate in the tissues might result, 
as Haldane* suggests, from the deficient sup- 
ply of oxygen to the tissues. 
F. H. Pie 
THE DEPARTMENT OF PHYSIOLOGY, 
CoLuMBIA UNIVERSITY 
ON THE HYDROLYSIS OF PROTEINS IN THE 
PRESENCE OF EXTRANEOUS MATERIALS 
AND ON THE ORIGIN AND NATURE 
OF THE “ HUMIN” OF A PROTEIN 
HYDROLYSATE 
In a recent paper McHargue! attempts to 
show that the nitrogen distribution of casein 
is not appreciably altered when hydrolyzed in 
the presence of five times its weight of starch 
providing that the hydrolysis is continued for 
only 12-15 hours. McHargue reaches a con- 
clusion which is decidedly at variance with 
that reached by myself? and by Hart and 
seriously vitiates the nitrogen distributions 
of a Van Slyke analysis and he explains the 
difference in the findings by his shorter hydro- 
lysis. However, he makes several astonishing 
1J. 8S. MeHargue, J. Agr. Res., Vol. 12, pp. 1-7 
(1918). 
2R. A. Gortner, J. Biol. Chem., Vol. 26, pp. 177- 
204 (1916). 
Sure, 7. e., that the presence of carbohydrates 
3 E. B. Hart and B. Sure, J. Biol. Chem., Vol. 28, 
pp. 241-49 (1916). 
4 Loc. cit. 
