PHYSIOLOGY: P.D.LAMSON 
525 
It has been found that the red count is under nervous control, as 
shown by the increase in the number of red corpuscles after stimulation 
of the vago-sympathetic trunks, after asphyxia of the brain alone, and 
after emotional excitement as fear, rage, etc. It was also shown that 
the adrenals play a part in this mechanism, as epinephrin has been proved 
to be one of the most powerful means of increasing the number of red 
cells, and as the chief physiological stimuli which produce polycythaemia, 
namely asphyxia, exercise, fear, rage, etc., all cause a reflex stimulation 
of the adrenals, and an increased epinephrin output. Removal of the 
adrenals was found to exclude the production of polycythaemia in 
asphyxia, fear and rage, and after the injection of pituitrin, although 
these same animals responded to the injection of epinephrin by the 
usual increase in number of red cells. Furthermore, removal of the 
adrenals is followed after several hours by a complete loss of control of 
the red count. 
When the number of red cells is increased in acute polycythaemia, 
we have seen that there is also an increase in haemoglobin, but not in 
proportion to the increase in number of red cells. This being the case, 
the blood is better equipped not only to carry more oxygen, but on 
account of the increased surface of the haemoglobin, to take up more 
oxygen per unit of time. The body is then better prepared to main- 
tain a constant oxygen content of the blood under various physiological 
and pathological conditions. 
We may therefore conclude that there is in the body a mechanism for 
regulating the red corpuscle content of the blood; that this mechanism is 
under nervous control, responding to nervous, chemical and emotional 
stimuli; that the adrenal glands play a part in this mechanism, and that 
the liver is the seat of the changes which increase the number of red cells, 
partly by a reduction in plasma volume, and partly by bringing cells into 
the circulation which are not normally present? 
^The terms red count, number of red cells, etc., will be used for the sake of brevity in- 
stead of the more exact phrase "Number of red corpuscles per unit volume of blood." 
2 This article is given in full in the Journal of Pharmacology and Experimental Thera- 
peutics, Vol. 7, Nos. 1 and 2 (1915). 
