24 CHIKANOSUKE OGAWA 



E (fig. 2). Vesicle not quite closed as yet and its opening turns 

 ventrally. The dorsomedial wall is thick. The vesicle has rotated 

 half-way. 



F. Determination difficult in this case, owing to disassociation. 



Exmnination 16 hours after operation. 



A I. The transplanted ear vesicle is somewhat oval in shape. The 

 thinnest part of the wall faces toward the brain, i.e., dorsomedially, 

 while the thickest part turns ventromedially. The cells composing 

 the thin wall are cuboidal in form; the thick wall consists of high 

 columnar cells. The cell layer is everywhere simple Close to the 

 medial wall there is a group of cells which probably represents a ganglion. 

 In this case, if the vesicle be regarded as in an earlier stage of develop- 

 ment, it might be said to have remained in its inverted position, since 

 at this time the lateral wall is usually thin; but to judge from the 

 development of the macula the vesicle must be older. Therefore, 

 taking the position of the macula as a criterion, the vesicle has rotated 

 back to its normal position. The presence of the ganghon at the medial 

 side of the vesicle bears out this conclusion 



A II. Due to injury at the time of operation, the brain is a little 

 deformed and in close contact with the wall of the ear vesicle, probably, 

 however, without any actual fusion. The wall is thickest ventro- 

 medially. Some parts of the wall are rich in yolk granules. The skin 

 has only partly healed over the vesicle. The whole appearance of the 

 specimen deviates from the norm and does not warrant a definite 

 decision as to the position of the vesicle 



A III. The whole shape is slightly abnormal. The wall is of uniform 

 thickness throughout. There are not enough criteria by which to 

 judge position 



B I (fig. 3). The vesicle is somewhat small and in section presents 

 an oval form. The wall is thick. The thickest part turns dorso- 

 medially, the thinnest ventrolaterally. The vesicle is evidently 

 retarded in its development. Since the position of the thickest wall 

 and that of the ganglion are reversed, the vesicle evidently has not 

 rotated. 



B II. No vesicle was found. 



B III. The vesicle is of oval type. The axis runs vertically, with a 

 slight lateral inclination. The thinnest part turns ventrolaterally and 

 the thick part ventromedially. A group of round cells, containing 

 yolk granules and pigment, is' present in the cavity. This cell mass 

 may have been taken in from the outside when the vesicle closed. 

 Rotation is nearly complete. 



C I. The vesicle is round and small. Because of the uniform thick- 

 ness of the wall, it is difficult to ascertain the degree of rotation. 



C II. The vesicle is small and round in section, but by measuring 

 the serial sections it is found to be elongated in its sagittal plane, 

 being especially narrow in its posterior part. A ganglion is closely 

 attached to the ventral side. Although the wall is of uniform thick- 

 ness, the general shape and position of the ganglion would certainly 

 indicate that the vesicle is still in the reversed position. 



