r891.] The Evolution of the Circulatory Organs. 245 
blood to flow upward, yet close and hold the column of blood 
upon any tendency to regurgitate. 
Now this writer claims that the valves of the veins have not yet 
become accommodated to the upright position of man, for there 
are several instances in man where the persistence of the valves in 
certain veins are not only useless.for their original purpose, but 
by their position are actually obstructive to the return of the blood 
to the heart. He asks, What earthly use has a man for valves in 
the intercostal veins which carry blood almost horizontally back- 
ward to the azygos veins? 
When recumbent they are actually a detriment to the free flow 
of blood. The inferior thyroid veins, which drop their blood 
into the innominate, are obstructed by valves at their junction. 
Two pairs of valves are situated in the external jugular and 
another pair in the internal jugular, but in recognition of this 
uselessness they do not prevent regurgitation of blood nor liquids 
from passing upwards. Where apparently most needed, such as 
venz cave, spinal, iliac, hemorrhoidal, and portal, there are none. 
The azygos veins have imperféct valves ; their rudimentary con- 
dition suggests that they may be of recent origin. Now place 
man on “all fours,” and these anomalies disappear. The veins 
which in man erect do not need valves will be seen to need them 
against gravity when on “all fours,” and as they are found in all 
four-footed animals; and where, in man erect, those veins which 
need valves but have them not, when on “all fours” will not 
need them. Valves in hemorrhoidal veins in quadrupeds would 
be out of place, yet their absence in man sacrifices many lives 
and produces untold suffering. It is difficult to escape from the 
consequences of Dr. Clevenger’s logic. 
Malformations—Cyanosis results from the foramen ovale, 
which establishes a communication between the auricles, remain- 
ing open after pulmonary respiration had been established, a ` 
condition permanent in the crocodile. An arrest of development 
at an earlier period may cause still greater imperfections in the 
formation of the heart. Thus, the septum of the ventricles is 
sometimes found incomplete, the communication between the 
cavities usually occurring in the part which is last formed, and 
