OF THE GREAT ANTERIOR VEINS. 
135 
the rig-ht auricle directly, but always pouring- its blood, like the posterior cardiac 
veins generally, into a larger venous trunk. 
The analogy thus indicated between the coronary sinus on the one hand, and the 
lower portion of the left vena cava superior or left vena azygos on the other, is ap- 
parent, not only in their likeness as to shape and structure and the disposition of their 
branches and valves, but also in the similarity of their situation, direction and con- 
nections with the heart, and in the resemblance, not altogether overlooked by anato- 
mists, of their respective openings into the right auricle. 
According to Rathke, however, whose authority is generally followed, the left an- 
terior primitive venous trunk in the human subject closes and entirely disappears in 
the progress of development, from the root of the neck down to the heart. But if, on 
the contrary, the coronary sinus, as found in the adult condition, in Man and some 
of the higher Mammalia, be, as is above suggested, the analogue of, or, to express 
the fact in another form, be the loiuer pervious portion of the left primitive vein, 
might it not possibly happen that, even on the fully-formed heart, some remnant of its 
upper occluded portion should still exist, above the valved entrance of the coronary 
vein into the coronary sinus ? 
Searching, accordingly, in the adult human heart, I have found, in upwards of 
twenty different instances, certain parts or structures (Plate I. fig. 1, o, I, v) always 
clearly distinguishable, though varying in distinctness, which, from their position and 
general character, are undoubted remains of the upper portion of the left primitive 
venous trunk. 
Analogous remnants of the left primitive vein are also to be seen, in all those Mam- 
malia in which — as in the Dog, the Cat and the Monkey — the same amount of oc- 
clusion of that vessel occurs as in the human subject ; and a comparative examina- 
tion of the arrangement of the veins in different animals, of the various instances of 
deviation from the ordinary condition in Man*, and of the metamorphosis of these 
vessels in human and other embryos, has sufficed to establish, beyond a doubt, the 
identity of the parts under consideration. 
The results of the entire investigation, together with due reference to the labours 
of others, may be conveniently presented under the following heads : — 
1. Development of the great anterior veins. 
2. Comparative view of the adult condition of these veins in Man and Mammalia. 
3. Analysis of their varieties in the human subject. 
* In the thirteenth observation out of twenty-four, I fortunately met with an example of double vena cava 
superior in the adult, a rare and interesting variety in relation to the present subject. Since then I have had 
presented to me a second example, occurring in a child between four and five years old. I may take the pre- 
sent opportunity of thanking Dr. Sharpey, Mr. Streeter and Mr. W. Bennett for aid in procuring materials 
for this investigation. 
