[qirdwood] right and LEFT HANDEDNESS 187 



looking down from above, it would be represented as a circle drawn from 

 left to right, passing upwards and to the right in a curved manner, then 

 still upwards and back at the same time passing gradually to the left 

 side of the vertebral column, then down the left side of vertebral column, 

 gradually passing to the centre thereof opposite the promontory of the 

 sacrum, where it divides into the two common iliac arteries. 



In this course the aorta gives off the two small branches to supply 

 the heart, the coronaries, then it passes on and where, it begins to turn 

 back and to the right side it gives off the large arteria innominata which 

 divides into the right common carotid and the subclavian, the carotid 

 supplying the right side of the head and brain and the subclavian the 

 right upper extremity. Passing on the arch of the aorta gives off from 

 the upper side of the arch the left common carotid and a little further 

 on the left subclavian, and then passing down the left side of the vertebral 

 column gradually coming forwards from the left side of the column to 

 the centre of the front of the column where it divides into the right and 

 left common iliacs to supply the lower limbs, the trunk and internal 

 organs being supplied by other branches on its way down. Now in this 

 course it does seem that the Ijlood supply to the right side through the 

 larger conjoined vessel the arteria innominata does receive a more direct 

 current and the two vessels being united and a little better positioned to 

 receive the more direct current, than on the left side where the two ves- 

 sels common carotid and subclavian are separate in their origin, and 

 given off at an angle not quite so favourable to the supply in directness. 



In the supply to the lower extremities by the two common iliac 

 vessels, the right iliac seems to get a little more direct supply than the 

 left, not from difference in blood pressure in either case, for it has been 

 found that there is no difference in the pressure on the two sides, as in- 

 deed, the physical law that liquids press equally in all directions would 

 preclude a difference in pressure but simply in direction, and the differ- 

 ence in direction being more easy for the current is the only difference, 

 but with the multiplication of 120 beats a minute the rate of pulse of 

 the newly born and before birth would make a multiplication of the 

 slight difference of 180 per minute, 

 60 



7,200 per hour. 

 24 



28800 

 14400 



172,800 per 24 hours. 



' Dr. Janeway, Blood Pressure. 



