'224 PROCEEDINGS OF THE ACADEMY OF [March, 



Villy/ and Gaupp.'' Shortly after I had begun the present 

 research a very important paper on the subject by Dr. Hans 

 Spemann appeared, treating of the earlier stages in the develop- 

 ment of the Eustachian tube in Rana temporaria.^ All the inves- 

 tigators mentioned state that the development of the tympano- 

 Eustachian passage in the forms studied is a very indirect one and 

 that it can be traced only v.'ith considerable difficulty. This diffi- 

 culty is attributed to the almost complete atrophy of the hyoman- 

 dibular cleft, which at an early period becomes so greatly reduced 

 as to be readily overlooked unless special attention is bestowed 

 on it. 



Of the investigators mentioned Goette correctly described the 

 degeneration of the hyomaudibular cleft, but his other results con- 

 cex'niug the development of the Eustachian tube may be disre- 

 garded, since his investigations were conducted at a time when less 

 favorable methods were at his disposal than we have at present. 

 From the results arrived at by the other three investigators a fairly 

 complete history of the Eustachian tube may be made out in the 

 case of Rana temj^orar-ia. Of these the work of Villy covers 

 fairly well the period of the metamorphosis, although his descrip- 

 tions are somewhat inexact,* and his conclusion, that the Eusta- 

 chian tube '' has almost certainly nothing to do with the hyomau- 

 dibular cleft," and that " the evidence oliered by the frog tends to 

 show that the two organs have no connection whatever with each 

 other," is certainly unsound, since such a connection between the 

 two has been established by the very careful work of Spemann on 

 the earlier stages of ihe tube in the same species. The correctness 

 of Spemann' s conclusions are corroborated by the results which I 

 have obtained in Bufo. Gaupp's chief contribution consists in his 

 calling attention to the appearance of the tubal Anlage at a stage 

 earlier than that in which it was first observed by Villy. For 

 further information concerning the results arrived at by these 

 investigators the reader is referred to the papers mentioned. 



^ "The Development of the Ear and Accessory Organs in the Common 

 Frog, Kana temporaria," Quar. Jour, of Micros. Sci., 1890. 



* " Beitriige zur Morphologic des Schiidels, I, Primordial-cranium von 

 Kanafusca," 3forph. Arb., Y, 2, 1893. 



'Spemann, " Ueber die erste Eutwicklung der Tuba Eustachii iind des 

 Kopfskelets von Eana temporaria," Zoologische Ja/trbijcher, 1898. 



^ As, for instance, he speaks of the tube as extending forward beneath tbe 

 palato-pterygoid bar, which it never docs, but, instead, passes beneath the 

 quadrate. Moreover, his figures shoAV it in the latter position. 



