OF ARTS AND SCIENCES. Ill 



m. 



CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 



OF THE MUSEUM OF COMPARATIVE ZOOLOGY 



AT HARVARD COLLEGE. 



No. 11. — THE RELATION OF THE EXTERNAL MEA- 

 TUS, TYMPANUM, AND EUSTACHIAN TUBE TO THE 

 FIRST VISCERAL CLEFT.* 



By Albert H. Tuttle, Boston. 



Presented June 13, 1883, by Alexander Agassiz. 



The recent revival of Von Baer's views f upon the development of 

 the accessory parts of the ear in mammals again puts the question of 

 their possible connection with the first visceral cleft in an unsettled 

 condition. Such being tlie case, a reinvestigation of the problem seems 

 desirable. It has been the aim of the author in the present paper to 

 go over the ground in the case of the pig, and, with the aid of a more 

 continuous series of embryos and improved methods of investigation, 

 to ascertain in how far this recently revived theory is worthy of ac- 

 ceptation. 



Historical Synopsis. 



In 1825 Rathke ('25, col. 747-749)t discovered, in the case of an 

 embryo pig half an inch in length, that on either side of the neck im- 

 mediately behind the head there were four gashes. These were suc- 

 cessively smaller from before backwards, and all had a transverse or 

 dorso-ventral direction. It was shown by dissection that they extended 

 through the walls of the throat into the pharyngeal cavity. He accord- 

 ingly called them " Schlundspalten " (throat clefts). At the same time 



* Prepared in the Embryological Laboratory under Dr. E. L. Mark. 



t Especially by Hunt and Urbantschitsch. 



t At page 130 will be found a list of the papers cited, the names of authors 

 being arranged alphabetically, the papers of each author chronologically. In 

 the body of the paper the number immediately following the name of the cited 

 author is an abbreviation for the date of the article referred to, and will enable 

 the reader to turn at once to the full title of the paper. 



