of Human Monstrosity. 241 



The heart by its increase soon appears to be too long for the 

 cavity in the neck that contains it, it becomes bent upon itself. 

 The mid portion of the canal forms a very acute angle with the 

 posterior portion which received the veins. The angle is the 

 future apex of the heart, whilst that part which receives the veins, 

 afterwards becomes the sac of the auricles. There is a constric- 

 tion also near its anterior extremity which denotes the bulb of 

 the aorta. 



The two vessels which have been described as arising from 

 the bulb of the aorta, are not the only vessels which come from 

 it. And here it is necessary to record one of the most striking 

 anatomical dicoveries of modern times, which was made by 

 Rathke about the year 1823. He found that not only in fishes 

 do branchial arches and cavities exist, but that these are found 

 during some portion of foetal life, as in the batrachia, so also in 

 serpents, lizards, birds, and mammalia including man. His ob- 

 servations have been confirmed and illustrated by Burdach and 

 Von Baer. In all these animals five pairs of branchial arteries 

 arise from the bulb of the aorta: they do not all exist at one 

 time, but appear in succession from before backward. They all 

 arch round the beginning of the digestive canal, (the anterior ap- 

 proximating as nearly as possible to the rudiment of the brain,) 

 and coalesce in the region of the spine on either side to form a 

 trunk, which is a root of the aorta: for the two trunks unite to 

 form that vessel. These arches are separated by deep fissures in 

 the sides of the neck, which penetrate even into the cavity of 

 the intestine. There are four pairs of fissures between the cor- 

 responding arches, exclusive of one in front of the most anterior 

 pair. The four posterior fissures on each side are gradually 

 obliterated, the anterior first disappearing, and the others in 



Vol. IV. Part II. H h 



