188 PROFESSOR MARSHALL AND EDWARD J. BLES. 



Huxley, in his "Anatomy of Vertebrates," gives the following 

 account of the changes undergone by the branchial vessels during 

 development.* " When the internal gills of the Batrachia appear, 

 each aortic arch which belongs to a branchial arch splits into two 

 trunks, — one which remains directly connected with the cardiac 

 aorta, and another which opens into the dorsal aorta. The vessels 

 of the branchial filaments constitute loops between these afferent and 

 efferent trunks, which always remain united by anastomoses. When 

 branchial respiration ceases, and the branchial processes and their" 

 vessels disappear, the anastomoses dilate ; the direct communication 

 between the afferent and efferent trunks of the second pair of 

 internal branchiae is re-established ; and they become the permanent 

 arches of the aorta. The anterior branchiae are replaced by the 

 carotid glands, and their afferent vessel is the carotid passage of the 

 adult. The afferent and efferent trunks of the third pair of branchiae 

 are converted into the stem of the cutaneous artery, and the afferent 

 trunk of the fourth pair of branchiae into that of the pulmonary 

 artery." This account has been very generally accepted in this 

 country, but is in many respects at variance with the conclusions 

 at which we have arrived. 



Goettef gives a careful and detailed description of the develop- 

 ment of the heart, dealing more particularly with the early stages of 

 its formation. He also describes at some length the development of 

 the venous system. His account of the arteries, and especially of the 

 branchial vessels, is, however, very unsatisfactory; and with regard to 

 the important changes undergone by these vessels during the transi- 

 tion from branchial to pulmonary respiration, he gives no observations 

 of his own, but merely states that they occur in the manner described 

 by Eusconi. 



BoasJ in a paper on the " Conus Arteriosus and Aortic Arches of 

 Amphibia," gives some important details concerning the development 



* Huxley, "A Manual of the Anatomy of Vertebrated Animals," London, 1871 ? 

 p. 192. 



t Goette, A., " Die Entwickelungsgeschichte der Unke : Bombinator igneus." 

 Leipzig, 1875., pp. 745-788. 



| Boas, "Ueber den Conus Arteriosus und die Aortenbogen der Amphibien," 

 " Morphologisches Jahrbuch," vii., 1881, pp. 488-572. 



