368 
PHYSIOLOGY: P. D. LAMSON 
for forcing out erythrocytes lying dormant in the capillaries of this 
organ, the red blood corpuscles known to have left the general circu- 
lation immediately appear in the blood stream causing an increase in 
number of erythrocytes per unit volume of blood. From these experi- 
ments it is concluded that the liver acts as a reservoir for erythrocytes. 
The process by which the liver increases the number of erythrocytes 
is thought to be a loss of plasma from the liver capillaries, together with 
a constriction of these vessels driving the erythrocytes on into the 
blood stream. It has been experimentally shown that the liver capil- 
laries constrict with epinephrin, causing a sudden diminution in size 
of the liver. This does not occur except to a slight extent when the 
hepatic artery is tied, and epinephrin injected intravenously, in which 
condition no increase in number of erythrocytes takes place. It is 
also of interest to note, as more fully described in a previous paper, ^ 
that Mautner and Pick^ have shown that the livers of cats and dogs 
constrict very markedly when epinephrin is perfused through them or 
intravenously injected into these animals. Rabbits however do not 
respond in this way to epinephrin, the liver capillaries not contracting. 
They also show no increase in number of erythrocytes per unit volume 
of blood when epinephrin is intravenously injected. Thus we have two 
types of animals, one the cat, whose liver responds to epinephrin by 
constriction of its capillaries and gives a polycythaemia, the other the 
rabbit, whose liver does not respond to epinephrin and in which this 
substance produces no polycythaemia. 
Concerning the mechanism which normally controls the red corpuscle 
content of the blood, my view was previously expressed that the adrenal 
glands play an important part in this process. Certain experiments 
were carried out in which the polycythaemia occurring in the normal 
animal did not occur in animals after the removal of the adrenals. Two 
additional experiments have been made which have strengthened the 
behef in this view. 
As previously shown, certain nervous phenomena are capable of 
producing a polycythaemia. This increase in number of erythrocytes 
must occur either by some entirely different process from that caused 
by the injection of epinephrin, or by some nervous influence directly 
or indirectly affecting the liver. Experiments in which the nerves going 
to the liver were stimulated, showed no increase in number of erythro- 
cytes. Furthermore in the experiments above reported, in which 
epinephrin is shown to have no effect on the number of erythrocytes 
per unit volume of blood in the rabbit, nervous phenomena known to 
cause polycythaemia in cats (which respond to epinephrin) caused no 
