44 ON PULSE FREQUENOY, ETC. 
from the above cardiograph law, that the systolic length varies as the 
square root of the diastolic. From these facts the relation of the 
nutrition of the heart to the time of heart nutrition (diastolé) and 
to the blood pressure may be deduced; for the systolic length not 
varying with the blood pressure when the pulse-rate is constant, it is 
evident that the cardiac nutrition must vary directly as the blood 
pressure in the aorta; and the systolé varying as the square root of 
the diastolic time, shows that the nutrition of the heart varies as the 
square of the time of nutrition (diastolé), for with a quadruple resis- 
Page 447. tance to the peripheral circulation, the heart would be four times the 
time in emptying itself, but it is only double that time, which demon- 
strates the statement. 
A complete logical explanation of the action of the pneumogastric 
can be given on this theory, by assuming that its function consists in 
diminishing the calibre of the small arteries of the coronary system, 
and always keeping them somewhat contracted. 
