334 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q8. 



the anterior mediastinum, was the thymus gland, considerably longer than in other 

 children, and extending downwards the whole length of the sternum ; behind this, 

 was a peculiar arrangement of blood-vessels. 



The heart, instead of consisting of 4 cavities, as in the natural structure, con- 

 sisted of a single auricle and ventricle, which were each of them large in their size. 

 A large arterial trunk arose from the ventricle, and ascended into the thorax, be- 

 tween the pleurae, immediately behind the thymus gland: it soon divided into 1 

 large branches, 1 of which continued to ascend, forming the aorta; the other 

 passed backwards, and proved to be the pulmonary artery. The aorta, having 

 reached the common place of its curvature, formed it in the same manner as it 

 usually does; sent off the vessels belonging to the head and upper extremities; 

 descended before the vertebrae, and passed into the abdomen between the crura of 

 the diaphragm. From the place where it began to form the arch, it was in no 

 respect different from the aorta of any other infant, except that no bronchial 

 artery was sent to the lungs, from it or any of its ramifications. The vessel which 

 proved to be the pulmonary artery, almost immediately divided into 2 branches; 

 one going to the lungs of the left, the other to the lungs of the right side. On 

 measuring accurately the circumference of the aorta, where it separated from the 

 original trunk, it was found to be exactly 1^- inch. On measuring the circum- 

 ference of the pulmonary artery, in the same manner, it was found to be -{-§- of 

 an inch; so that it was -j^. of an inch less than the aorta. 



The vena cava inferior, having been partly surrounded by the substance of the liver, 

 entered the lower and back part of the auricle. The subclavian vein of the right 

 side crossed over to the left of the mediastinum, where it joined the left subclavian, 

 and formed the vena cava superior. This passed down on the left of the ascend- 

 ing, and before the descending part of the aorta; it was then joined by a trunk 

 formed by 1 large veins, which came out of the lungs, and which were situated 

 immediately behind the pulmonary arteries: the union of this trunk with the vena 

 cava superior was continued into a large vessel, which gradually expanded itself 

 into the auricle. The vena azygos ascended on the left side; received some 

 branches which passed under the aorta from the right, and then entered the upper 

 and back part of the vena cava superior: there were no bronchial veins. From 

 there being neither bronchial arteries nor veins, it would appear that the pulmonary 

 arteries and veins, in addition to their usual offices, performed those of the bron- 

 chial vessels. The liver was not divided on its upper surface by the suspensory- 

 ligament, but had a considerable cavity scooped, as it were, out of its substance; 

 which in shape was adapted to, and contained the heart: it was also, in some other 

 particulars, rather different from its natural shape, but not sufficiently so to re- 

 quire being minutely described. The rest of the infant was not found to be dis- 

 similar to any other. 



It is a well-ascertained fact, that the blood receives a florid hue from the influ- 

 ence of the air on it in the lungs; and this change is supposed to be effected by 



