ORIENTATION OF THE EAR VESICLE 23 



Protocols of experiments 



Examination 15 to 30 minutes after operation. 



A. The ear vesicle is located in the area bounded by the brain and 

 the endoderm, and is superficially embedded in the latter. The wound 

 is still wide open laterally. The brain is quite intact. The vesicle 

 is open toward the medial side. The wall is thick, indicating an early 

 stage of development. A shght disassociation is shown in the lower 

 part of the vesicle, otherwise it appears normal. No rotation has as 

 yet occurred. 



B I. On account of disassociation, no study could be made. 



B II. The inverted ear vesicle seems well fitted to its new position. 

 The skin has not yet entirely healed over the wound. The opening of 

 the vesicle turns medially and slightly dorsally. No rotation as yet. 



Examination 3 hours after operation. 



A. The vesicle is already closed. It cannot be determined from its 

 appearance whether the two edges participated equally in the closure 

 or whether one of them took a predominant part. The lateral wall 

 of the vesicle is about twice as thick as the medial and its outer surface 

 is convex, while the medial wall is rather flat. The skin has already 

 healed over and is in contact with the lateral wall. Normally, the 

 medial wall should be thick and the lateral wall thin in the early stages 

 of development; since in this vesicle the order is reversed, it must be 

 assumed that the vesicle is still in an inverted position. 



B (fig. 1). This case presents about the same picture as B II (exami- 

 nation 15 to 30 minutes after operation). The vesicle is open toward 

 the brain. The skin has not yet healed over the wound. No rotation. 



C. Sections destroyed. 



Examination 4 hours after operation. 



A. Vesicle already closed. The lateral wall is flat, the medial wall 

 convex, and the two are of equal thickness. It is difficult to determine 

 the position in this case, but judging by the general shape of the vesicle, 

 it might be said to be normally situated. 



B. Vesicle already closed. Because of the uniform thickness of the 

 vesicle wall, the position is difficult to make out. 



C. Vesicle closed. No efficient criteria can be obtained. 



D. Sections destroyed. 

 Examination o\ hours after operation. 



A. The lateral wall of the vesicle is convex, the medial wall flat. 

 The latter shows the mark of a healed wound. Most probably this 

 vesicle is still in its abnormal position. 



B. The vesicle has not closed, the opening faces mecHally. No 

 rotation. 



C. Vesicle closed. The dorsomedial wall is less tliick and may with 

 certainty be taken for the original lateral wall. The vesicle has turned 

 half-way. 



D. The lateral wall of the vesicle is thinner than the medial wall 

 and the arrangement of the cells here is irregular, suggesting the healed 

 trace of the vesicle. Rotation is complete. 



