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RaTHKE!), in 1857, claimed that the external carotid (carotis 
facialis) arises from the ventral vessel which, in the embryo, leaves 
the third aortic arch near its base and passes forward into the neck. 
The internal carotid (carotis cerebralis) he supposed to be made up 
of the rest of the third arch after its dorsal portion becomes 3eparated 
from the fourth arch. These two vessels are present in a young 
embryo of the fourth day of development before any neck is formed. 
During the formation and elongation of the neck, RATHKE supposed 
that the basal portion of the third arch became elongated to form 
the common carotid, and, in this way, the ventral vessel mentioned 
above, and the dorsal prolongation of the third arch would be carried 
forward and form the fork of the common carotid, separating it into 
external and internal divisions. 
Mackay ?), in 1888, says in reference to RATHKE’s conclusion: 
“It may be established by direct observation that at a period when 
the third arch is still dorsally connected with the fourth (during the 
sixth day) it is the common carotid, not the internal carotid, which is 
continued from the dorsal end of the arch to the head. The external 
carotid branches are not therefore the product of the ventral trunk 
but are to be regarded simply as visceral and parietal branches of a 
dorsal vessel. The ventral trunk remains as a small branch from the 
subclavian or innominate arteries to the front of the trachea.” 
“Further, the vessel on the ventral aspect of the throat, which RATHKE 
supposed became the external carotid branches of the common carotid 
stem, is seen to be of small size compared with the dorsal vessel 
and to be connected at its base with the subclavian artery.” 
In the interval between RATHKE’s paper and that of Mackay, 
Foster and BALFOUR had (1874) given an account of the development 
of the carotid arteries of birds founded on the idea of RATHkE. His 
observations were amplified and this account by Fosrer and BALFOUR 
was the standard one until the appearance of Mackay’s paper. 
It must be admitted that none of these writers were correct. But 
the account given by Mackay, although more recent, departs farther 
from the actual course of events than that of the others. 
KASTSCHENKO in his paper “Das Schlundspaltengebiet des Hühn- 
1) H. Raruke, Untersuchungen über die Aortenwurzel und die von 
ihnen ausgehenden Arterien der Saurier. Wien. Akad. Denkschr., Bd. 13, 
1857. 
2) Joun Yure Mackay, The Development of the Branchial Arterial 
Arches in Birds, with special reference to the origin of the Subclavians 
and Carotids. Phil. Transact., Vol. 179 B, 1888. 
